Id never really heard of post-rock before, those are great. I have a bit of a bias towards insturmental music so its easy for me to get into, plus I love it when the music itself has meaning or depth to it since thats what I grew up on. Im really bad at finding music though, lol.
I could definitely know more about classical and orchestral as well but I know where to get started. Phillip Glass is great for contemporary classical music. And youve probably at least heard of several older classical artists and would recognize their songs. My absolute favorite is Hanz liszt, then theres Debussy, Mozart, Chopin, etc. Theres this really great CD that I cant seem to find that has a really great cross section of their music. The difficult thing I find about classical, at least personally, is that the pianist can make or break the song depending on how well they play it and original recording dont exactly exist, lol. And since its not terribly popular most recordings on youtube tend to be pretty bad, not to mention that sound quality really really makes a big difference (true for orchestral as well).
I dont know as much about orchestral, but Tchaikovsky (nutcracker, swan lake, sleeping beauty) is one of my top favorite song writers. Also Andrew Lloyd Webber (Phantom of the Opera), who you mightve already heard, but both are harder to judge since I attach them to their stage performances as well (although I would definitely recommend going to them).
But yeah, take these with a grain of salt:
http://www.youtube.com/watch?v=hEnfZjqMSy0 - La Campanella (Franz liszt)
http://www.youtube.com/watch?v=OCSevzJQ2-Y - Rondo Alla Turca (Mozart)
http://www.youtube.com/watch?v=79UfWizjGiQ - Reverie (Debussy)
http://www.youtube.com/watch?v=Ah_fDwREp6g - Nutcracker - The Presents of Drosselmeyer (Tchaikovsky)
Definitely more but Im going to try and find that CD too.