Well, when I finally get back to Best Buy, I'm getting compilations for each of the ones listed. Who is that in your sig, Schubert? Give me some specific shit from him. Wagner is fine too.
Stuff like that.
for schubert i would start with sym. 8 and piano trio no. 2
wagner is a bit trickier though... there are plenty of best of's of his music that contain instrumental sections from his opera's, which is fine of course.... i've got a few myself but to really get into wagner you need to get complete opera's.
the best one's to start with are Das Rheingold and Der Fliegende Hollander... these are shorter and more accesible opera's but still quite excellent. if still interested get the entire Ring Cycle and Tristan Und Isolde
compilations are good places to start for new comers (it certainly helped me) but really to get into classical you'll eventually need to get complete pieces and not just best of type stuff.
some favorites from the composers you listed that are good to start off with would be:
chopin- scherzo's, ballades, nocturnes, mazurkas, waltzes, preludes, etudes
bach- brandenburg concerto's, triple concerto in a minor, b minor mass, toccata and fugue in d minor
rachmaninoff- piano concertos 2 & 3, sym. 2