I watch tons of movies over and over. Two I would not, that I loved, are:
Slingblade
Lars and the real girl
On the Beach.
That ‘Vegas’ movie with Keaton.
Good movies but depressing as Hell.
Sophie’s Choice. Incredible movie, I remember the whole audience sobbing. No way will I ever watch it again.
Hell, I’ll probably like the next Hobbit movie but I’m not looking forward to seeing it this Friday night.
All Quiet on the Western Front. Cried so much I gave myself a headache. No need for that again, thanks. 
Marnie. I saw this for the first time a couple of months ago. I love my Alfred Hitchcock: The Masterpiece Collection set, but I’ll never watch Marnie again. I really hated the way Hitchcock set up this film. I liked the first 30 minutes or so with Marnie as a pathological liar and thief, but the rest of the movie with the sexual aspect between Marnie, Sean Connery, and Marnie’s history was difficult to watch. I’m glad I saw the movie so I know what people are referring to when they talk about Hitchcock and his attitude towards women.
There Will Be Blood
Agreed with Schindler’s List but a good part of that is its length. It’s not the sort of film I’d watch in bits and pieces but neither can I set aside a four hour block to sit and watch it.
I think it was on this forum that someone called Happiness “the best movie I never want to see again”.
I generally agree with you, but I did watch the Sixth Sense several times. I was so impressed with the plot structure the first time I watched again to see if they “played fiar”, that is, with respect to the Bruce Willis character. It turns out they did.
Another I watched several times is Groundhog day. I don’t remember why I originally decide to rewatch it, but I discovered that there are some aspects of that film that really don’t get your attention the first time through. Most people, like me, after seeing it once can only recall how tedious it was to have that alarm clock go off each morning playing Sonny and Cher. After several viewings a subtle subplot began to emerge, which is probably the actual plot of the movie. Try it sometime and see if you have the same experience.
I’d draw a difference between movies like “The Sixth Sense” and “The Usual Suspects” and comedies like “The Hangover”.
In the first case, the surprise twist is what makes the movie; they’re not nearly so interesting once you know the secret.
In the second case, there’s not really a “twist”, just a sort of odyssey to figure out where Doug is, and the odyssey is the point of the movie, not where Doug actually ends up being.
I can rewatch movies of the second type all the time, but not the first ones.
Robocop. It was a perfect comment on the 80s, but the brutal, sadistic violence made me never want to watch it again.
Blackhawk Down. Excellent movie, but I just can’t watch the scene where they’re trying to reach the guy’s femoral artery to stop the bleeding. Can’t do it.
I Spit on Your Grave.
One of the better films from a genre I despise. Likewise, I’ll never see it again.
Pulp Fiction: loved it when came out but I haven’t watched it in years and have no real desire to anymore. Whether thats because references to it are so common or I’m just sick of Tarentino in general I couldn’t say.
Munich The Spielberg/Eric Bana film about the Israli squad sent after the 1972 Munich Olympics terrorists.
The Road. Love it, but draining.
Farewell My Concubine. Chinese opera has never been my thing but by the end of that movie, I was coming around. Of course, the end was so devastating that I sobbed for an hour on the way home.
I rarely feel tempted to watch a Coen brothers’ movie again.
Which is strange because I really enjoyed virtually all of them the first time.
I’d say it’s still a perfect comment. If anything, corporate power has increased…
I’ll add one more film to the list: Lilya 4-ever. Good movie but one of the most depressing I’ve ever seen. And I’ve seen a lot of movies…
The Green Mile.
Forest Gump. Strange that a lot of my friends have watched this movies several times. Heh, my Mom threw away my Dad’s DVD of this movie because she got so sick of him watching every other day. (To hear he tell it.)
Saving Private Ryan. Saw it in the theater but can never watch it again mostly for the scene where the soldier is pleading with the nazi not to kill him with the knife.