I don't know BIRDIE well enough to comment on whether it works for today's audiences. I will say that if you have a multi-cultural cast, HAIRSPRAY is a recognizable title, is upbeat, and employs a cast of all ages.
I saw a high school production a couple years ago, which may not be the same version that would be licensed to your group, but several scenes made me cringe, particularly the stuff with the Shriners.
