This museum is both my and my 3 year old daughter's favorite spot in Pittsburgh. We recently got a membership so we can go as often as we want for the next 2 years. She loves the art room where she can mold clay or paint on easels. I love it because I don't have to worry about paint ruining anything!
Her other favorite rooms are the upper floor where they have great activities for younger children. This includes bird seeds to play with, train tables, a giant light peg board, sand tables. For the parents it is great as there is seating. You can sit down for a few minutes and watch your child. It is a nice stop to relax on your way through the museum. She also loves the water floor. It is amazing. The rain jackets they provide are great. If you have a child who really loves water make sure you bring a change of clothes.
The changing exhibits are great as well. I like knowing that most times there is going to be something new for us to check out. If you live in Pittsburgh and have young children seriously consider a membership. It is worth it!