I love
Carmen. It's actually one of the very first name I remember really loving and am not afraid to admit today :) In like 2nd grade I named a bear I won from a carnival,
Carmen, and I've really like it ever since. It's one of those name I can EASILY picture on someone of any age.
Carmen Apollonia is a too much of a mouthful I think - how about
Carmen Apolline instead?
Either one sort of makes me think of caramel apples, though - not necessarily a bad or good thing but something to consider.