To showcase your system (great video and audio):

A Bugs Life
The Fifth Element
Godzilla
Lost In Space

Several fantastic surround sound scene can be found in Cutthroat Island, though the video is a bit lacking. For excellent sound in a drama you might want to try The Man in the Iron Mask or The Mask of Zorro.

Some of my favorite discs also include George of the Jungle, Mouse Hunt (Yeah, yeah, I know), The Mask (hmm, lots of mask movies), Star Trek: Insurrection and a bunch of others. It's a great format for any kind of movie. :-)