http://www.wikipedia.org/wiki/Wicked
(pick the musical in the list)

Here is a big write up from wikipedia. I haven't seen the musical but I've heard it is great. I don't know about age appropriate issues though. I attempted to read the book about a year ago but I just couldn't get into it blush but I have heard really great things about the musical. Hope it is fun if you get to go!!! smile