I was a music major in college, but my school failed to instill a deep love of classical music in me. I like most of what I know, and those I like I like a LOT, but I'm not likely to listen to the classical music station on the radio.
As a former pianist (oh, I'm so rusty it makes me sad), I loved playing Debussy and Chopin. Mozart, too. Mozart's and Bach's music is perfection. I'm not a religious person, but you listen to Mozart and Bach and are ready to drop to your damn knees and proclaim that these guys were touched by the hand of God.
Now instead of playing piano, I sing in a chamber choir, and I love most of the sacred music we sing. This past year we did the Mozart Requiem for his 250th (200th? I don't remember) birthday.
For our last concert, we sang Faure's Requiem (so beautiful) and a little-known piece called "The Seven Last Words of Christ" by a French composer named DuBois. I love, love, love that one.
Other faves: Debussy "La Mer" and "Clair du Lune", Bach's cello suites, Barber's "Adagio For Strings", Dvorak's "New World" Symphony.
Justin24 mentioned a Chanticleer "Ave Maria" earlier in the thread - which one did you mean? I have a recording of them doing the Franz Biebl "Ave Maria," and it's just the most beautiful piece of music you've ever heard.
Really, you can't beat a good "Ave Maria."