Judging by pic #2 and #4 you have a fairly steep slope past the deck. Is that correct? Please confirm or deny before I go any further.
BTW, you have a very-very-VERY nicely formed speciman of SM-tree. Congratulation!

Hi George! Thank you! I love this SM tree, too!

Yes, you are right. I do have a fairly steep slope past the deck. Even where the deck is, the slope is steep, so you see how much lower the tree appeared to be in the photo when it's placed between the Annabelles?

While the steep slope provides me with a fantastic view of the ravine and the green belt, I can't plant much around there!!! Sigh...

'...I can't plant much around there!!!'

Why? You know where I'm going, don't you?

I see a nice small lawn tree (SM) encircled/underplanted by 3-4 blue ES and the whole bed positioned in a lawn somewhere in front of the balcony/off the center.

If you decide to go with plan B as shown in a last picture, I'd enlarge that bed and wouldn't plant the tree any closer than it is standing right now.
You would need 4-5' clearance between trunk of the tree and the deck as well as the pathway to the steps from the entrance. In a short few years crown of the tree will be much wider than it is right now and you don't want to prune it because you have to cut 'this encroaching branch', but rather prune it for symmetry at your discretion.
Good luck.
Let us know what have you decide. Or better show it. :-))

First, let me say..beautiful property Ostrich.

I agree with George (or should I say, I agree with where I think he is going)...IMHO, there is already enough going on in the Annabelle bed. Neither the SM or the Annabelle will be best served by crowding them all in together. The SM deserves a place of it's own as a specimen out in the lawn yet not too too far from the deck, with or without underplantings. Planting too close to the deck may mean having to transplant (or drastic, unnatural pruning) in a few years and why set yourself up for that? You have a lovely setting in which to add your very nice specimen SM. I would follow nature's design already existing in the rest of the yard which appears to be very woodsy, yet open, very natural and most importantly, noncontrived and uncluttered as say a more urban garden might be. I guess what I'm trying to say is...I would spread 'em out and keep it loose! Good luck....yg

George and yg, thank you so much for your great suggestions!

Right now, I am leaning towards planting it next to the deck and the steps, but like you both pointed out, it should not be too close. I will need to do some measurements to see where to put it, and whether it will then affect the sprinkler line or not.

I will keep you posted!

Thanks again.

Just an update for you all, esp. for George and yellow girl - I think I found the perfect spot for the SM tree now! It's actually directly right across from the angle of my deck. It will be about 6' away from the railings. I probably won't hit the sprinkler line there either! I plan to enlarge the existing bed for Annabelle in order to incorporate the tree into a larger bed. Maybe I will do some underplanting too... now, is there any space there for some Blue Billow!? Oh no, am I gonna open up another can of worms here? Sigh...

Here's a picture to illustrate what I am talking about:

What do you think? Should I start digging now? :-)

If you need my stamp of approval you got it!!!

'.... is there any space there for some Blue Billow!?'

Of course. As soon as you remove that weed some people call 'grass' or 'lawn' and lay a real bed, 5-6' wide all way around your deck, you'll immediately see that other side of the steps IS CALLING you to make a symmetrical bed over there. In my visual guestimate it should be about 7' deep and should have plenty of room to accomodate anything you will be enabled to next time when you visit this forum.
Now you probably understand better where I'm going :-))

BTW, I see another tree standing on a deck and I have a strong suspicion that nearby nursery got you on their 'frequent-buyers' list.
Let me guess. Pink Diamond?

Looks good to me too!....Just one thing...if you are planning to put BB or other plants, I would get my entire scheme together and have all plants on hand before dropping the SM. Most importantly, find that irrigation line so you will know EXACTLY where you can plant and then form/shape the bed accordingly. Can't tell you how many times I had everything perfectly arranged and partially planted, only to find that plant #4 (for example) could not be planted where I intended and then of course it's back to square one.
Good luck....yg

George and yg, you are the best! Thank you!

Now, in answer to your questions, George, I actually have 3 ES already on the other side of the deck! I guess you meant THAT side of the deck - it's way over to the left of the photo - is that what you meant? I was wondering if I could have somse Blue Billow in front of the Annabelles? The thing is, it does get some noon sun there - isn't Blue Billow supposed to require much shade and not a drop of noon and afternoon sun at all? Anyway, here's a pic from the "other side" of the deck:

I got the 3 ES and many perennials around there too.

In terms of the "other" tree on the deck, George (ha! I knew you would notice that! :-)), it's actually another SM. I saw another lovely one there and I just had to get one for my friends! They have a new house without landscaping, so this is a housewarming present... now, don't tempt me about Pink Diamond trees! I actually saw them at another local nursery a couple weeks ago. I resisted the temptation! I just don't have the space for it... sigh....

yg, thank you for the advice. That's why I hang around here, because you guys are just so good!

Thank you again, George and yg!

I just wrote a nice detailed and lenghty (of course!) post and it was lost.
Trying again.
YG is 100% correct. You have to have all shrubs on hands AND find out where the sprinkler line is before planting you anchor tree.
I had so many disappointments when perfect thoroughly thought plan was ruined by some unexpected ledge or huge rock laying just under 2-3" of top soil.

Yes, I was talking about this particular bed.
As soon as you finish planting your deck's bed (next week, next month or next year) you'll realize that this(ES) bed look skimpy and need to be increased to watch the bed on another side of the stairs(deck's bed).
That will involve major reshuffling and not necessary will be to the benefits of the plants' well being. The younger the shrubs the easier this job could be done.
Again, as I said before, I'd rather see white blooming SM-tree surrounded/offsetted by the blue ESs than a white-white combo of Annabelle+SM. Matter of taste of course, since culturaly ES and Annabelle are fairly identical.
Also, don't forget that by the time SM will be in full bloom your Annabelle will be or soon will be in a green stage and that may create somewhat clashing effect, I think.
So, I'm suggesting to use 2-3 ES on a sides/around SM and to separate your pair of Annabelles and move the right one to the far right end of the railing where the entrance is.
In this order: A-ES-SM-ES-A.
There is a possibility that A will eventualy outgrow ES (or maybe not), but at least give a thought to this idea.
Maybe just remove one of the A (or both) and plant it(them) in a bed currently occupied by ESs.

Re: BBillow.
'... isn't Blue Billow supposed to require much shade and not a drop of noon and afternoon sun at all? '
Absolutely unsubstantiated notion. If ES doing good there, BB will do good as well.
One thing is for sure, I wouldn't be looking for place for BB in a deck's bed for one and simple reason, you don't want to waste 40-50 days in a height of the summer for its 'ugly duckling' period.
Good luck,
G

George, thank you so much for your very thoughtful response! I truly do appreciate it. It's great to have someone who shares the same interest, and someone who is generous enough to share his wealth of knowledge too! Thank you!

George, I have figured out where the sprinkler lines are now! I gave your ideas more thoughts. I agree that the ES bed now looks a bit skimpy. It does need to come out more. However, I am not sure if I want the big ES to be in front of the Annabelles though - I think they might be a bit distracting there. I prefer something shorter, probably some perennials or some small shrubs.

Now, George, given that the SM tree will be in front of the Annabelles, and that I would prefer something shorter, and probably something that would take some shade under the SM tree, what perennials or small shrubs would look good there? What do you think? Any blue flowering perennials/shrubs would look good there? I was wondering if caryopteris Sunshine Blue might look good next to these beauties there? I think that the combination of the golden foliage and the blue flowers might look great next to Annabelle. What do you think?

Thank you again for your very helpful responses!

I'm still opposing the idea of A and SM to be in a close vicinity (think about large mature and droopy A, not a small and upright as you see it right now), but you are THE boss...

'...I was wondering if caryopteris Sunshine Blue might look good next to these beauties there?'

Your wish is my command, maam!
Something like this? :-))

Here I have two established C.clandonensis 'Dark Knight' on a flanks and young C.incana 'Jason' (aka 'Sunshine Blue') in a front.
I had in mind to suggest to use Caryopteris there for the complimentary blue, but stop short because of the three factors,
-a) cold hardiness issue,
-b) during the bloom time it become literaly covered by bees and I don't think you want to lure them to your deck,
-c) it would rather prefer full to almost full sun in order to bloom at its full potential.

In any event, Sunshine Blue being C.incana is less hardy than any of the C. clandonensis.
If C.cl. is reliably hardy for you and you want a yellow (to say the truth-limy) foliage then old good 'Worchester Gold' should be your choice.
In my garden both Kuyshu and Dark Night being planted in full sun usualy have a simultaneous bloom peak, first-second week of August.
Here is Kuyshu as of today and it need one more week to be called 'in full bloom'.

George, thank you for the helpful pics and information on caryopteris!

I probably need to think of something else then... if the Homigo in my containers were hardy in zone 5, I would have them planted in this area! But they are not...

Anyway, I see what you mean about putting the SM tree and Annabelle in such close proximity. However, I think that given their very different textures (in terms of foliage and flowers), and different height, I think it should be OK, esp. that by this time of the year, my Annabelles are turning a lovely green, while the SM tree will just be starting to bloom.

That's why the underplanted items are so crucial! They will act as the crucial link between the two hydrangeas.

How about some hostas? I said this with some reservation because I have plenty of deer that love hostas as their salad...! But if I used one that has great foliage colors and shape/form, that could work great under my little tree. Also, Liquid Fence has saved my Sun Power and Guacamole this year... for this area, I think that something like my Paul's Glory (which are wasted between my ES right now, as they are completely lost there), or June, or Regal Splendor might work well here. Perhaps I can just dig up my Paul's Glory and give them some growing space here!

Another thought would be astilbes. I love these guys! Mass plantings of them here could be quite a lovely sight. However, my concern is that they tend to have rather short bloom time and so the effect is too short-lived.

What else might you suggest for this space, George?

"Your wish is my command, maam"!
BTW, George, I'm a guy too! :-)

Hostas might work, but it has to be something of the Regal Splendor/Krossa Regal magnitude. Sagae?

George, your idea of Sagae is very intriguing! I never considered such a giant there. I guess it may just work with one such beautiful giant hosta there! Let me think about it more... I am very intrigued by this idea indeed.

Thank you again!