I've probably said it before but, Dune.
Yes, but which one? The David Lynch film from the 80s or the miniseries from 2000? They're both good, in their own ways. I'd be happy with either. Or both.
As for suggestions, I'd like to see you guys do Inception, Red and The Sorcerer's Apprentice. And I agree about Branagh's Henry V, but if you do that one, you need to do his Much Ado About Nothing as well. If only to demonstrate why you never cast Keanu Reeves in Shakespeare.