If you opt for a tree that doesn't shed its leaves each fall, you'll shiver during the winter months or pay more in heating bills. If you plant your trees in a location directly south of your home, you're going to block perhaps more sunlight than you bargained for, which is advantageous only for those who live in climates that are very warm year-round. Regardless of where you're planting trees, make sure you don't plant several of them very close together. Sure, that might give you maximum shade, but it could also produce a wall effect, blocking air flow from your home and possibly increasing the heat and humidity behind them. You want to be able to enjoy your trees but also feel a cool breeze blowing through them.
Nothing stops the force of roots.
Another option you may want to consider is a trellis. They're sold at nearly every home-improvement store or warehouse. You can grow inexpensive, quick-growing varieties of vines on your trellis. This is an excellent way to give yourself shade, a little privacy and relatively fast results. Your gratification comes much sooner than if you were to plant a tree in the same spot.