Christmas: The Nightmare before Christmas and Rudolph the Red Nosed Reindeer Halloween: ALL THE SCARY MOVIES!!! (Heck, I watch them year round. XD)
Hogfather and The Color of Magic are probably going to be my new Christmas movies, now, though, lmao. Both are hilarious. Hogfather's really deep, though, at points. I thought it was pretty...well...ballsy for it to say the things it was saying at certain points.
Halloween: Nightmare Before Christmas, Night of the Demons, Gegege no Kitaro, Killer Pad Thanksgiving: Great Yokai War, Inuyasha movies, Karate Kid 2, The Thanksgiving That Almost Wasn't, Tenchi Muyo Christmas: Sailor Moon: Hearts in Ice, Home Alone, Holiday Wishes, Grinch (both versions), Santa's Slay, Bleach: Diamond Dust Rebellion, A Christmas Carol (Jim Carrey version), Super Mario Christmas specials, Lifetime and Hallmark holiday specials, Ranma 1/2 Christmas
Halloween: A bunch of random horror movies from my collection
Christmas: Frosty the Snowman and Frosty Returns, How the Grinch Stole Christmas (both the original animated version and the Jim Carrey version),the stop-motion Rankin-Bass classics, The Nightmare before Christmas, A Year without a Santa Claus, Mr. Magoo's Christmas Carol
Valentine's Day: Corpse Bride (one of the few romances I actually like XD)
I also watch the first few episodes of Futurama on New Year's Eve.
I know it has absolutely nothing to do with the holiday itself but I think I've watched The Lord of the Rings trilogy every Christmas since those movies came out. The whole holiday just doesn't feel right without them anymore...