I love the name Clarisse. I prefer this spelling over Clarice, because I think that spelling looks a little bit plain and old lady-ish, and also doesn't have the Clarisse McClellan association, who is a book character I love (mentioned before by another poster).
I think Clarisse looks and sounds beautiful. It can also be shortened to the more down-to-earth Reese, Claire, and perhaps Clara. How lovely!