Organ Stop Pizza has been a place that I remember going to as a kid. Now I can take my daughter there (at a nicer, newer location) to hear the music of the large organ. She really seems to enjoy it and she dances along to the songs, especially when they play Disney songs (which you can request too). Also, they have cat puppets that do a little dance to a few songs that she really likes. Some songs I request are Chattanooga Choo Choo (sounds like a train) and Star Wars, both of which sound really neat with the organ and other instruments they have.
The pizza itself is okay and reasonably priced.
The one con is bring cash as they do not accept credit/debit cards.