Claire is nice :) It does sound sophisticated. The only thing you can't do with it is use it as a middle name with the first name
Anna!
Spelled as
Clare is just a good, spelled a Clayre makes me want to say it "klay-uh" and not "kl-air."
Clarissa is prettier than
Claire, but not as sophisticated.
Clara, for me, is like Buttercup and
Clover; it is a cow's name.
I also like:
ClariceClarita
and
Clarisse (very French, that one ^_^)