Hmm... dunno if these will work for you, but you could try checking out:
*Xenosaga Episode II soundtrack disc 1, track 13 "Communication Breakdown"
*Blue Dragon original soundtrack disc 2, track 24 "The Seal is Broken"
*Super Mario Galaxy's "Arch Nemesis King Koopa" and "Showdown on the King's Planet" are pretty epic sounding and both have some choir in them
*Kameo: Elements of Power "Hero's Theme," "The Badlands," "Danger in the Sky" oh heck just listen to that whole soundtrack.
*Also, try to track down some samples from the new Alone in the Dark soundtrack. A lot of that might be of interest to you.
The rest of these never had official soundtracks, so you'd have to find rips:
*Beyond Good & Evil: "Dancing with Domz"
*Phantasmagoria (old PC game): "Consumite Furore"
*Red Steel "choir theme" (IGN had this track up as a download before the game came out, they still might)
*Super Smash Bros. Brawl opening theme
That's all I can think of off-hand. I'll edit if I can come up with any others.
Edit: A lot of those tracks have some electronic or rock influence in them as well... if you want exclusively traditional orchestral/classical-type stuff, skip all but Kameo and Smash Bros. Brawl. But I'd recommend you not doing so.