Ratta wrote:
Short answer: Everything!!!
Long answer: Read all the replies. Explore. Be on the lookout for birds, reptiles, coyotes, spiders, snakes and other goodies. The sun illuminating the spines of the cactus in the Cholla garden can give your camera a workout. There are areas which attract rock climbers and you can get some awesome pics of the climbers during magic hour. The nights are dark and beautiful.