I agree that Aliens should be a classic...awesome film - I'm settling down to watch Blade Runner this evening.
I watched Blade Runner on Netflix instant for the first time recently. I don't know what took me so long.
I would call it a classic. I still haven't seen One Flew Over the Cuckoo's Nest despite having stolen (read: borrowed and forgot to return) it from a coworker like three years ago. Oops.
It's a pretty good movie. I should read the book too at some point.