A few spring to mind readily,

"One Flew Over The Cuckoos' Nest". I thought Nicholson was superb and, although I don't enjoy some of his work, his recent work such as "As Good As It Gets" and "About Schmidt"(?)has also been excellent.
"To Kill A Mockingbird" Probably my favourite film AND book!
"The Colour Purple". Moving story and beautifully framed.Like "Dances With Wolves", it needs to be watched on a big screen.
"The Godfather trilogy" I liked them all but part 2 was the weakest.
"Schindlers' List" Very moving and should be compulsory viewing.
"The Sting" My first movie-date was to see this film so I have fond memories for various reasons! Maybe a little dated now but, even on the strength of the sound-track, worthy of inclusion.

I'm sure I'll be back with some more later.

C-flat.