Went to the Institute of Arts last night to see a special exhibition of a local guy who did illustrations for kids stories etc. in the 20's - 40's. It was AWESOME!!! This exhibition is only there until Sunday; I cannot recommend it highly enough!! And very kid accessable too!! I really hope they publish a book of his stuff, I'd buy it in a heartbeat!
http://new.artsmia.org/exhibition/richard-holzschuh-storybook/ There's also several other special exhibitions going on, and of course the amazing permanent collection.
And best of all, the entrance fee and most of the exhibitions (including this one) are entirely FREE!!!