Did you read the book first? That's soured me on more than a few movies. Most notably The Shining. II only saw it once when it came out, so I could well be overrating it. I loved it at the time though and bought a Blu-ray the moment they hit the shelves. (My wife has a copy of the book which I would like to read.) I couldn't believe the same guy responsible for Hulk made it.
Some that may not have been mentioned. I grew up surrounded by WWII vets, including my father, and ended up loving movies like these. Paths of Glory The Bridge on the River Kwai Battleground Twelve O'Clock High Das Boot Patton Casablanca The Big Red One Stalag 17 The Train Lawrence of Arabia The Deer Hunter
Movies Ive seen a million times: Kung Fu Hustle Dredd Sicario The Sandlot Tropa Elita 2 The Devil Wears Prada
couple of randos i didn't see mentioned... Patton - just can't stopwatching it once you start Fifth Element - always have to stop on it if i see it on
Mac and Me. (Sorry if already posted several times -- that would make sense.) Spoiler Rushmore (seriously) Miller's Crossing
Field of Dreams Seven Silence Of The Lambs Munich Goodfellas Batman Begins Road Trip American History X
A couple more that I forgot I can recite beginning to end: This is Spinal Tap Weird Science More contemporary entries to the "classic" comedies: The Hangover The 40-Year Old Virgin Anchorman
Casablanca The Godfather/The Godfather Part II Bonnie & Clyde Taxi Driver Chinatown The Graduate Titanic Once Upon A Time in The West A Clockwork Orange/The First Half of Full Metal Jacket/Spartacus/Lolita/2001 A Space Odyssey Apocalypse Now 8 1/2 Jaws/ET the Extra Terrestrial/The Color Purple/Schindler's List Maybe, Fight Club Pulp Fiction
My favs that haven't been mentioned: Dances With Wolves Lonesome Dove Whale Rider Close: Hoosiers Rudy
In addition to others previously mentioned: The Terminator I don't think they are perfect, but I can rewatch a lot: The Losers End of Watch