[DanL]

Well, since this is for a trip, that kinda rules out some of the best-made films like American History X, Requiem for a Dream, or Shawshank Redemption - those aren't really sitting-on-a-bus-and-watch movies. You need one of those movies without too much of a real in-depth plot - I'd suggest the classic Pulp Fiction, but somehow I doubt that would fly with your teachors or advisors.

LotR, maybe, but the bus ride would kinda ruin the atmosphere. I'd suggest (like many other before) Pirates and Holy Grail. Ocean's 11 would also be a good choice. Dr. Strangelove is a classic, but if you don't have a lot of crazy global-dictator still-living-in-the-cold-war-era type of students, most of the bus will be crying to turn it off. Robin Hood: Men in Tights or History of the World Part I are good for some cheap laughs (Spaceballs is good, but not funny after the first time), and Shrek and Finding Nemo are always good fall-backs. Of course if you've completely given up on finding a movie with any sort of decent plot at all, you can always turn on Starship Troopers.