My favorite fairy tale is 12 Dancing Princesses. It would make a great play! Plus if it is going to be for kids theatre, it has that built in lots of parts for lots of kids thing going for it.
Other than that I would think about some of the russian fairy tales. The snow maiden is one of my faves. I also like The Firebird. Russian fairy tales tend to be a little bit more balanced...not sure why that is. BUt I enjoy them a lot.
Hope that helps!!
Adina mama to B 4/06 and E 8/13/12 (on her due date!)