I'm not going to argue with the folks that say Avatar's overall plot was quite cliché; because I agree. However the world James Cameron constructed over the dozen years he worked on it is just incredible; all the more incredible is the effort he and his team put into assembling the design into a tangible experience.
The Dark Knight just plain kicks ass in every way possible. It's not perfect, but it might as well be.
Oh yeah, I've been getting into films with what I like to call a perspective-shift at some point. For fear of spoiling any one movie, I can't use any example. But I'll list a few:
The Sixth Sense is probably the most popular, commonly known perspective-shift
Shawshank
Fight Club
A Beautiful Mind (the shift is halfway through instead of near the end)
Memento
The Truman Show is just one big ol' perspective shift, haha
Same for Inception
I watch movies over and over, which unfortunately manages to keep me from widening my gaze as often as I'd like. But I do learn a lot about life or the movies themselves via repeated viewings.
Shawshank 26 times
Fight Club almost 15 times
A Beautiful Mind almost 14 times
The Truman Show at least 14 times
The Italian Job at least 12 times
Searching For Bobby Fischer at least 14 times
The Dark Knight at least 12 times
The Green Mile at least 12 times
Up at least 6 times
Eternal Sunshine [Of The Spotless Mind], Memento, Inception, and Up In The Air are right around 4 each, but they'll all catch up sooner than later.