Here are the movie soundtracks that impressed me most of all. The first 3 are from my college years (approximately).

I used to have the soundtrack LP from "Zorba the Greek" (1965), and I loved it. The tunes were composed by Mikis Theodorakis. I don't know who performed them. Anybody know what the featured instrument was? It sounded sort of like a hammered dulcimer, but I suppose the Greeks might have a different name for it. Then again, it could have been a zither.

"2001: A Space Odyssey" (1968) had both Richard Strauss' "ALSO SPRACH ZARATHUSTRA" and Johann Strauss' "THE BLUE DANUBE."

"The Pawnbroker" (1964) had a soundtrack that was mostly jazz. I didn't own that album but I think I borrowed it from a friend.

Jumping ahead a few years: "Koyaanisqatsi" (1983) had a soundtrack composed by Philip Glass.