I don't know if you will consider it, but we have a similar shade problem in the dining room which is on the side and backside of the house. We planted banana trees. They shade us from the sunner sun abd die back in the Fall so we get the sun in Winter.

If bananas wont' work, try a sweetgum. They grow fast and have beautiful Fall color. Caution, they drop seed balls and sucker from the roots but make good shade.

i don't have one but i always admire the chinese pistache trees around here. the summer canopy is light rather than dense shade and the fall colors can be beautiful (for trees that color well in the southeast u.s.).

Here is a link that might be useful: chinese pistache

jeff_al: Thanks for the input. There are some that have been planted along the main street downtown here, but they're just getting out of the gangly age and I wasn't sure if they'd really look nice as they mature. From what I've read, they get better as they get a little bigger.