Evergreens are terrific to block any views where you'd rather see green than other houses, etc. I have a few at the back by the fence line, and instead of seeing the back of another house, I just see green trees year round and I think it's wonderful. If you like bird watching at all and attracting them to your yard, putting feeders up under big old trees is the perfect way to get the most birds. So back to whatever suits you and what you want to see there.
If you like seeing more birds, maybe finding out which attract what birds might whittle down your list of what you'd like to plant. Visiting local nurseries to find out which trees are really hardy and problem-free might help get the list down further. Driving around, have you seen any trees that you really love?
