What movie should I take her to?

I'm going to take this girl I like to the movies on Monday. I'm probably going to ask her out too. What movie should I take her to? We're both 13 and I think we're going with friends of ours that are going out. I was thinking Avatar, Alvin and the Chipmunks, or The Blind Side. She mentioned that she heard Avatar was "Good, funny, and romantic". So I'm probably going to take her there. If I do, should we see it in 3D or no?