HONK! is also great. All of the characters are animals and for the most part it wouldn't matter whether you cast a boy or girl. SEUSSICAL, LITTLE WOMEN and MILLIE are all great choices as stated above, but MUSIC MAN and FIDDLER happen to have a large amount of good female characters, though there are plenty of men involved as well. I once licensed an all female 1776 at a Catholic girls' school. It was a great way to learn some history and they played all the male roles as men. The pony tales worked for the period as well.