I don't know about a musical, but I've been toying with the idea of turning the 9 plays of John Cariani's Almost, Maine into a song cycle. I would start working on it, but I can't figure out how to get in contact with John Cariani...
Fear of Flying, Erica Jong's wildly successful (but now largely forgotten) 1973 novel (musical should be named after the line's most famous phrase and concept, "ZIPLESS &*()!," or if that's too pearl-dropping, just "ZIPLESS".... although FEAR OF FLYING is a perfectly fine name for a musical)