you definitely need to pick something you like, we all have our favourites, and no matter how visually stunning a movie, if the story doesn't interest you it's still a waste.
however, I would certainly recommend something dark. one of the first movies I watched on my x35 was the dark knight, and I nearly unplugged my plasma and moved it into the living room. I knew I would never watch any movie on it again, there was no need when the x35 was actually blacker!
my other favourites for a new display(you'll probably be able to guess when I first got into the home theatre bug based on the first few)
-transformers(any of them)
-any of the Iron Man movies
-Gattaca(for no real reason in particular, I just like the way this movie looks)
-the Hobbit, or any of the lord of the rings
-lucky number slevin(I just really like this movie, but you could make a case for it visually as well. the wallpaper in this movie is absurd, haha)
if you're at all in documentaries i'd also recommend the planet earth series. absolutely stunning in content and presentation
Displays: Samsung PN64F8500/JVC X35
AVR: Pioneer VSX-1130K, 7.1/5.1.2 audio
Sources: HTPC(Enby), PS3, XBOX360, Wii
Control: Harmony One