Here are some pictures of my Camry with a Thule rack
Right now the rack only has 2 bike racks on since i have needed the space for carrying kayaks. I also have a clamp style ski rack which I don't really like because salt coats any skis on top. This summer i made a "coffin" to put my skis in and we will see how that works this winter.
As for gas mileage you do loose a little bit, but Im still getting around 440 miles per tank on the high way and only a slight decrease when you add things to the top (like canoes or kayaks).