The AZ Science Center is one of our all-time family favorites. The kids enjoy the hands-on exhibits and always seem to find new things each time we visit.
During our last trip in March, the kids emptied grandpa's wallet of pennies with the penny-flattening machine. They also enjoyed the interactive video/light exhibit and the musical instrument room. The adults' favorite things included the gyro-bike in which the guest rides a bicycle around in a loop-de-loop (wear closed-toed shoes, there is a height restriction). Don't skip the fourth floor, where I rode a Segway scooter, my own personal favorite.
Tip: Be warned that on hot summer days or days coinciding with school vacations, the museum will be packed and you may have to wait in a long line at the entrance.
Arizona Science Center.