Hi Ted,
I must admit I don't really know a great deal about classical music ( love all those big concerto's like Greigs etc) but "Variations on a Theme of Paganini" by Sergei Rachmaninoff along with Debussy's " Claire de Lune" would have to be my 2 favourite classical pieces. I really love that part of the movie where she dances for him.
Actually (back in the 80's)) picked up the complete musical score in miniature on the Variations on Theme of Paganini. Had the crazy notion I'd try and sequence the 18th variation ( in steptime , as I'm a lousy player) Unfotunately it was pre internet days, so no help available, and it was too difficult to try and work out what some of the strange sounding instruments ( I think they possibly had latin names) let alone the actual score. They were written in clefs?? I've never seen before. I really had some whacky ideas back then( still do).

I have a couple of boxes of original old sheet music stored out in the garage. Some of it dates back to the 20's & 30's. Way before my time.

best wishes
Rikki