Well, to start, it looks like you pencil drew the door to the WC as an inswing. DO NOT DO THAT. The architect knew what he was doing making it an outswing. Small enclosed WCs are dangerous with an inswing door, as if someone passes out in there (happens more than you care to think about), they fall against the door (the only place they can fall) and then it is literally dead weight for an EMT to try to "move" out of the way. Hinges are inside the room/not accessible and so the EMTs have to destroy the door and waste precious minutes getting to the sick person.

So, starting there--you need some space for the door to swing OUT.

You might consider some built-ins, or a pass-through cabinet door to your closet, or what I'd probably do--switch the locations of the WC and the shower (and make the WC door be a pocket in the side, instead of a swing on the front). Why? Because then you can hang your towels on that blank wall. As is, is there room to hang towels for your showers?

You could really make that a nice drying off area/dressing area if the WC and shower were switched.

(But, you'll want to enter the toilet from the side, so you don't see the toilet directly as you enter your bathroom.

Can you change the window layout? Here is the plan Summerfield drew up for us. We changed a few things, but we really like the layout. Our bathroom is a bit smaller than yours will be.

I second dekeoboe's suggestion to use Summerfields plan - it's great! I am using it too :)

Thanks for the inout and suggestions!
kirkhall, I hadnt thought of the issues with the door swinging in, so I appreciate it. We figure that door will remain open much of the time, so we'd like to avoid blocking the windows. I like the idea of switching the shower and WC a lot! It seem slike it gives the shower more privacy, as it will have a glass door, so it would feel very exposed right inside the entryway. And there is NO room for towels, drying off, etc. in the current location. The shower could also be a bit longer/bigger, and then an area with a bench, some hooks, towel bars and towl storage right outside of it...this could work.
The WC will be right inside the entry, though, and you suggest entering from the side--not sure how thqt would work with the tub there?
Is that tub HUGE or normal? I haven't shopped those yet, but it seems immense??

dekeoboe and miruca, thanks for sharing summerfield's design--it's really nice! We have those windows there to mimic an original aspect of our home that we really love--those twin windows appear in the cnter of our house currently, so the architect suggested we use those same windows in the new master space, and I really like it. He centered them on all three outside walls--pretty cool! I definitley want them in front, the side and back I'm not AS concerned about, but I do sort of like them. Especially the ones in the back (near the WC, currently) so I can see outside in the backyard, if neccessary. With our kids, dog, and all other manner of chaos, a place to take peeks out is always a good thng. so, I don't want to completely cover up that back wall, leaving no windows at all.
Here is the front elevation, so you can see the twin casement windows we are replicating in our new space:

I'm going to work on the plan of swapping the shower with the WC and see what I can come up with...

I'd welcome any further suggestions or examples, too. Like I said, I don't; really know the first thing about bathroom design or trends--I'm getting schooled right now :)

For such a large bathroom, the shower seems small. I agree that you should swap the WC with the shower. But then perhaps you would consider having the shower span the entire far window wall, with a glass wall/doors across the entire shower. That would allow light to pass through, but give you a large luxurious shower (room for two even).

I also notice in the drawing that the bathroom is up two risers. Why? Personally, on the occasions I need to use the bathroom in the middle of the night, two steps up would be a tripping hazard for me.

pricklypearcactus, thanks for your feedback!
Wow, I never considered teh shower spanning the back wall--that would be HUGE--I love the idea, but it might be too much for us :) Will consider it though, for sure...I defintiely think I will make the shower bigger than it is currently drawn, if we swap it to that other side.

The 2 steps up in the plan have been removed. He originally did that to allow us to keep our family room celiing (the existing space below this) in tact, but we've decided to bring down the ceiling, add some lights, etc, and make the new bathroom floor even with the bedroom. I agree, the 2 steps up would be a pain!

I'm thinking the set-up could be something like this photo, but a bench from the tub deck into the shower...and then the WC would be at the opposite end of the tub.

That should work, right? The only issue now is figuring out how to align the door on the WC...

If the tub and shower are on the back wall, couldn't the WC then be a bit bigger where you could use a pocket door instead?

I think that I like the tub centered under the windows on the side wall...which leaves the shower to one side, and the WC to the other. I just really like the windows to the backyard, and I'd them to be "usable" rather than inside the shower or above the tub. But I don't love the idea of walking right in to the WC area, even with a door...although if the door is pretty....