Read Coleridge's poem "Christabel" for a Geraldine with a difference!
I prefer it to Gerald, which is unusual for me: usually I'd go for Joseph rather than Josephine, Robert rather than Roberta etc. But not enough to ever use it. I used to play with a really boring Geraldine when I was little: perhaps that had influenced me.
Geraldine Mary has got a lovely 1930s air about it! Geraldine Tiffany, for instance, would be dreadful.