Steve Reich, [album: Music for 18 Musicians], on the basis of The Edge of the American West’s recommendation. Actually, that’s not 100% true: I wouldn’t have bothered to look into the Reich piece had I not already been obsessed with another of Reich’s works (viz., [album: Tehillim / The Desert Music]). Both are trance-like and beautiful.
On the basis of that same EotAW review, I’d like to get an MP3 version of Philip Glass’s [album: Symphony No. 9], but there doesn’t seem to be such a thing.