The Arizona Science Museum was a blast not only for the kids, but also for the adults. The Science Center is huge and definitely deserves a few hours to fully enjoy it all. There are roughly four floors, with anything and everything you can imagine. They had exhibits on senses, space, natural phenomenons, the human body, psychology, etc. The exhibits were informative, hands-on, and computerized, and they varied with each room. The planetarium was absolutely fabulous. The guide who took us to Mars during the planetarium show was friendly and extremely knowledgeable.
Here is the web address for the Science Center: http://www.azscience.org/