Excellent soundtracks I can think of now:
Metal Gear Solid (all of them)
Homeworld (none of that new age space stuff but some cool arabic themes)
Prince of Persia (2008, some may not like the game that much, but the music was awesome. Sands of Time trilogy music wasn't half bad either)
Final Fantasy (not all the games but some of them are quite grand. FFX is my personal favorite, music-wise)
Devil May Cry 4 (nice and over the top)
Shadow of the Colossus (the music was half the game, some of the prettiest tunes I ever heard)
Armored Core (particularly For Answer IMO, very good music)
Okami (very suitable Japanese themes)
And of course GTA... (Vice City was the best)