I got a purple leafed sand cherry for my backyard. They are normally shrubs but you can find them trained into a tree form. The sources I found said it should top out around 10 feet. I wanted something small for the yard that wouldn't shade all my roses but provide some shade for my 3 dogs since the backyard is sunny through the hottest part of the day. I had a little structure built for the tree to keep the dogs from watering it to death. As you can see someone thought it was her own personal hang out spot.

The tree has little white flowers in spring that are lightly scented. Mine is blooming right now.

Or maybe you could go with a hydrangea. I have Limelight and it blooms mid summer. Mine does just fine with mid afternoon through evening sun. It is supposed to get 6-8 feet tall and wide but mine has been a slow grower. Maybe that wouldn't be big enough for you?

I have a Miss Kim (dwarf) lilac anchoring one of my flower beds. I think they are supposed to stay around 6 feet tall, but ours is around 10' and would like to keep going. I especially like it for the incredible scent (even better than our other lilacs), the fact that it blooms a bit later than the others, and that it is such a mannnerly little tree/bush. I am no pruning expert, but it really keeps it's shape.
Good luck with your choice!
Kim

pagoda dogwood, ironwood/blue beech, viburnum, serviceberry

Hmmmm... what is that they say about "the best laid plans"?

All of these suggestions were great, but I ended up falling in love with a ref-leaf rose (Rosa glauca, I think) when I saw it at a nursery. It gets about 6 feet tall here, and two of them will look great arching over at the back of my border, I think.

The other benefit is no more searching for those little green caterpillars that skeletonize the leaves (sawfly larvae?) and blend in so well on regular roses. On the reddish leaves, you can see them from across the yard. :)