Slate has a pretty good roundup of alternative Xmas movies. Not straight up Xmas movies like It's a Wonderful Life (which I go back and forth on between thinking it's a complete piece of shlock or a flawed work of genius), but under-the-radar ones. This is when Xmas is almost incidental... but nevertheless a character in the movie. And whose role might be bigger than initially thought.
Like, say, Die Hard.
Michael Agger's analysis of the great Die Hard is an extremely funny one -- I hadn't ever thought of the scummy Euroterrorists as anti-Santa Clauses. And it's probably the best one on the list.
I would also like to point out that in nearly every one of his movies Shane Black makes Xmas a character. (Lethal Weapon, despite the fact that it stars the odious Mel Gibson, should probably be on this list.)
Also, I would add Gremlins (a childhood favorite) and Go! (hipster, ecstasy fueled X-mas.)