I agree with Daniel's recommendations. I don't have about 3 of those that he recommended, but I heartily agree with the rest.

The first DVD I put in my player to test out my system, and one that I used to demostrate to visitors to my home theatre: Tomorrow Never Dies. You get to demostrate the sound very early on.

Since then, I've found a few others (those Daniel mentioned included). I'd also add Face/Off, GoldenEye (the gun barrel opening shot gives a very spacious soundstage), Armageddon, Deep Impact, the Jackal, the Siege...and Daylight.

Daylight's surround starts very much the minute the movie starts. The explosion scene starts at around the 15 minute mark, and after that, I think, the sub and rear speakers never stops.

So if you want to really show off your system, Daylight is a must.

Of all the Alien titles, I think Alien Resurrection has the best 5.1 sound. The first 2, I thought that in the 5.1 version, the dialogue is much softer than the effects/music, whereas the Dolby Pro-logic version actually sounded better. (The first two movies are also pre-Dolby 5.1 anyway).