Off the top of my head, the Titanic posters are the most beautiful. I also like Midnight Cowboy, although they didn't use the best shot in the movie for their posters. There is a frame where Jon Voigt is walking down a street amidst a sea of people in soft focus, with only his head and cowboy hat in focus above the crowd. Whenever I've had the opportunity to buy a movie poster, I've passed it up, and I always regret it. If I only had more walls.
I agree with you on Apocalypse Now.