I don't like Christmas movies, but "Love Actually" makes me happy. That and I love Alan Rickman. "Ten Things" is a very fun movie with some great quotable lines, like:
Walter Stratford: My insurance does not cover PMS!
Kat Stratford: Well then, tell them I had a seizure.
and my favorite:
Kat Stratford: You can't just buy me a guitar every time you screw up, you know?
Patrick: Yeah, I know. But then, you know, there's always drums, and bass, and maybe even one day a tambourine.