As a Caroline, I will gladly tell you all about how it's the very best name. :)
(Although let me say that I do love Madeline-- the spelling thing can get a little out of control. Madeleine, Madaline, Madelaine...and the nickname Maddy seems inevitable and covers Maddisons, as well.)
I've NEVER had a nickname in my whole life, something I really do appreciate. I have pet names (weird things that people close to me call me), but no one has ever been able to nickname Caroline. There was a short period when friends thought it was funny to call me Carol. Nixed that pretty quickly.
Lest we forget, if it's good enough for a Kennedy...