My quarter is finally over, so I can finally get down to some serious viewing! This thread has reminded me of a lot of holiday movies that I don't usually get to watch, but definitely should.
I always start with The Holiday. It's not a very good movies, but everyone in it is pretty damned charming. One thing I noticed when I watched it this time around is that, even though it takes place during the days leading up to Christmas, and the day when all the stories climax is presumably Christmas, Christmas actually doesn't ever really get mentioned. It's like a Christmas movie full of people who don't actually celebrate Christmas. Very odd.
Anyway, the other stuff I watch:
Harry Potter and Lord of the Rings have been mentioned in this thread, which shouldn't surprise me. All the Rankin/Bass stuff, especially Rudolph the Red-Nosed Reindeer. A Charlie Brown Christmas is a favorite in my family. My family also does a lot of the older classics:
It's a Wonderful Life - I'm surprised nobody has mentioned it yet.
Miracle on 34th Street
The Bishop's Wife
The Sound of Music
Scrooge (A Christmas Carol) - The 1951 version, starring Alastair Sim, who plays the best Ebenezer Scrooge ever.
Heidi - The Shirley Temple one, with the greatest high-speed sled chase ever filmed, and "Herr Sesemann!?"
My offbeat favorites are Scrooged and Elf. A Christmas Story is a great movie, too. And I really like About a Boy, too.
My all-time favorite holiday movie, the one I save for last, is Love, Actually. The only part I don't like about it is that stupid "to me, you're perfect" scene. Everything else about it is great. A modern-day classic, as far as I'm concerned.