A couple of my favorites that are just a bit out of the ordianary are Acer palmatum 'Ruby Ridge" (aka Crumple Leaf) and Acer plamatum 'Kandy Kitchen'.

For brightness and interest you might consider a semi-dwarf palmatum from the 'Sango kaku' group like Acer palmatum 'Fjellheim', 'Winter Flame', 'Aka kawa hime', or 'Beni kawa'. All are quite similar so what ever is available.

All would be good, as would many others, but will be borderline in your zone.

MJH

Thanks for the suggestions MJH...I like the Fjellheim. Saw it recently in the MM color flyer. I also liked the Orange Dream in there as well. What do you think of that one? Or is it kind of twiggy? You see i have a butterfly in this spot right now...but was since i've read more about the other JMs...yes...i'm wondering what else is out there and since this is a pretty protected spot, I wanted to be adventurous and put something there i maybe couldn't put on the north side of house for wind/hardiness reasons. I'll check out the other ones you listed. What about shidava gold? That looks rather neat in the MM brochure too. FYI...a mountain pieris and seiryu will be nearby if that helps anymore. For groundcover i was thinking some aureum creeping jenny and tiarella wheryii.

also there's a beni otake in the area (protected as well). I checked out the kandy kitchen - pretty neat looking...kind of looks like my beni otake.

As for the Orange Dream and Shidiva Gold, they will both grow upright and a bit twiggy at first. You will see very small thin chutes on new growth, but after a few seasons they chutes will take on a better form. I have not grown Shidiva, but I think both to be medium shrub-like trees. I don't think I would plant either of them if I was looking for that one special tree.

It is really hard to give the best recommendation--especially when you are willing to look for something out of the ordinary.

Here is a list that I recently put together of some of my favorites:
Aratama
Beni hoshi
Beni kumo-no-su
Butterfly (Oregon)
Edna Bergman
Ellen
Hoshi kuzu
Nuresagi
Oregon Sunset
Oshu beni
Ruby Ridge
Seiryu
Shojo shidare
Shigitatsu sawa
Tsukushigata
Villa taranto
Wabito
Yubae

Since you seem to have the option to plant some things of various size, many might work.

Tsuma gaki and Tsuma beni are also very bright and nice, but tender. After reading your recent statements, I was kind of feeling like you might try a veriegate. My choices would be: Shigitatsu sawa, Amber Ghost, Purple Ghost, Peaches and Cream. All might be a gamble.

Narrow down your list and I will be happy to comment further.
MJH

You might also try Acer circinatum 'Sun Glow' or Acer shirasawanum `Aureum' or Acer shirasawanum `Autumn Moon'.

Dax

Yes, I think the autumn moon would be a great one!!!!

I agree with mjh most of the suggested cultivars are dicey ...you say your in zone 5 b and I guess that is possible but wi is 200+ miles north of me and I'm 5b so you must be near the lake or in a strange zoneal area..I would classify most of WI as 5a-4b. If it is protected from strong winter winds and close to your house you may be ok . I would be careful with both aureum and autumn moon ...they will burn in hot morn or aft. sun but agree autumn moon is less likely to do so although mine DID. Yubae may be the best for you from what you have asked about and seems VERY hardy and is smallish nice color and shape and grows fairly slowly ...I really like mine ...another that I have recently purchased but have no personal experience with is Pixie ...it is related to the bloodgood i believe a sport of such and therefore should be VERY hardy and smaller and fit the bill...mine is really nice like a minature bloodgood but better and more distinctive lookin' not just another typical upright red jm IMHO...David