Not making any attempt to come up with any kind of exhaustive list. Also, it doesn't help that I've seen far too few of all the films that have been made, so I'm drawing from too small of a pool.
And I won't try to answer the question in terms of how to avoid embarrasment when pitching a film to Hollywood executives. Okay, well, I would say that the easy answer to your specific question is to see as many films as reasonably possible, which I'll bet you're already doing. A caveat to that might be, see as many of the ones you can bear to. I know I'm not one to often force myself to sit through a film that I know or suspect that I just don't or won't like just to be culturally literate. I suppose that's about balance. See something in order to be culturally aware. Or, choose to not sacrifice an hour and a half of you life on something that you loathe or that you just don't care for.
I don't mean to hijack your thread, but this questions interests me in terms of, say, what films might be recommended for the sake of cultural literacy, or, maybe for artistic relevance and personal growth, or to simply learn what's already been done.
1984. Because it's such a damn good film adaptation of the book. And because the story's value will only increase...not that it
will be valued.
The Godfather. Because it's a masterpiece, and popularly and properly considered to be one.
Casablanca. Ditto on the masterpiece score. Ditto on the cultural relevance, even still. It's economical storytelling and filmmaking, and yet manages to satisfy.
I'm disappointed in myself for not yet having seen more of Hitchcock's films, as I should have, and as I should be. But I think it's safe to say that, of the ones I have seen,
North by Northwest is a good contender to be on such a list. The stars, the masterful suspense, the sense of adventure, the romance. It's all there. And it's pretty popular and well known.
Bringing Up Baby. One of the best, and also has to be one of the archetypal Hollywood romantic comedies. Been a long time since I last saw it. But one of most wonderful Hollywood couplings ever.
Jaws. The first blockbuster.
Well, sort of, not really, but....
Star Wars. If for no other reason, then at least for its impact on popular culture...which is all around us.
Metropolis. Only saw this recently myself, thanks to Netflix. Not perfect. I wouldn't say it's a masterpiece. Not hardly. But it's still a pretty amazing film. Wouldn't get by today's gatekeepers. But thankfully, today's gatekeepers weren't in charge back then.
Edit: After further thought, I suspect that that's not true. At least, not quite true. I suppose that you could say that comtemporary films like Total Recall (2012), Elysium (though I haven't seen it yet), or others are today's Metropolises. So I suppose Metropolis could make it by today's gatekeepers. It would probably just need some editing, changing round, maybe some additions and subtractions, and no doubt need to be fitted into the BS2. And voila.
Apocalypse Now. Becauses it's a magnum opus. A masterpiece. A tour de force. You could start with its contributions to
sound.
Puhhff. Must be many more. But I guess I'll stop there. For now. =)