Kidspace Museum in Pasadena is one of the area's top children's museums. It is a great way to keep the kids occupied for a few hours. The exhibits are educational, but, for the most part they don't hit you over the head with it. Kids can have fun playing in the miniature Arroyo Seco without knowing or learning anything about the Arroyo Seco, but the information is there if you want the added educational value. If you're local or visit often, the $100 annual membership for a family of five (2 adults, 3 kids) is an excellent deal, allowing 15 visits for the price of two and a half. Additional kids are $25 per child over 1.
There are activities at Kidspace to inspire, educate and entertain infants through middle school kids. Parents are required to supervise kids, but there are staff on hand to assist and interact with children in all activity areas.