Vampire Hunter D Bloodlust. Great movie to if you like anime. I lent this to a friend who has been on the fence so to speak about "cartoons" after he heard it his comment was something to the effect of holy chit where can I buy that!!
I can't say enough about Air Force One. Every time I show someone the opening scene on my surround sound system, they are thrilled when you hear the guards seemingly moving around the room shouting. It's one of the best examples of surround sound I've heard.
And, like everyone else has said, The Phantom Menace is a spectacular mix. Especially the Pod Race sequence.
As others have already written, Saving Private Ryan is the one must have for sound. Not just the beach landing either, but also the final battle. It is the standard. That said,
One of the very best surround effects, and apropos given the date, is the angel of death (killer of the first born) from Prince of Egypt. The sound moves slowly from one part of the room to another.
Twister makes extremely heavy use of surround (no one has mentioned it yet?!).
I love the street crossing scene in Toy Story 2. Many people flag the opening of TS2 but I think the street crossing is even better.
Bugs Life generally has muted surrounds but they come alive when Flick goes to town and during the final confrontation with Hopper, beginning with the attack of the "bird."
Castaway makes heavy and effective use of surrounds, both for the plane crash and to create ambiance on the Island.
Elizabeth has some very good, very believable, interior of a castle type echoey effects, as when she is addressing the lords on the issue of the Church of England.
I second Neils nod for Titanic, the scene after Rose grabs the ax and wades back. One of the best surround effects.
And Matrix, U-571 and Das Boot, Star Wars I, Airforce One Titan A.E, Fifth Element, Independence Day, Sixth Sense (ambiance)...
Terminator 1, Jurassic Park 3 in dts is very good since it gets right to the dinos and not having to wait 1 hour untill the surround sound gets action.
if you have pro logic, the akira soundtrack in Japanise
I can't believe no one has mentioned The Perfect Storm!
You'll swear that your all wet when the film is over, the storm sequence rages through your soundfield for more than an hour!