Lena Horne was originally set to co-star with Bert Lahr, but it turned out to be Delores Gray instead. However, when Betty sings "Catch Our Act at the Met," she does a terrific imitation of Lena Horne..
I saw this on Broadway a thousand years ago and it was delightful. I remember it ending with The Party's Over, which was as perfect a song choice as could be imagined. You left the theatre feeling elated and sad at the same time. A cherished memory.