Until they get to the 20th century it's often boring. Bach, Beethoven, Mozart aren't boring they're just really tonal because it's the classical period but teachers don't know how to relay it so that it's interesting to our 21st century ears. Late Beethoven starts to get interesting and more harmonically complex.
What do you think of Schoenberg? Mahler is another favorite of mine.
You're right, learning about music before the 20th century was kinda boring. But, it wasn't really the music, for me it was my teacher. He spoke in almost monotone voice for every lecture (think Ben Stein w/slight voice fluctuations, lol). If he had made his lectures more lively, I would have gotten into it more.
Now Schoenberg is da man. His way of making a formal structure for atonality was simply genius. Everybody after him owes him a great deal of gratitude.
My favorites right now are Chopin, Beethoven, Bach, Mozart, and Scott Joplin. I got a few Chopin pieces, Beethoven's entire Moonlight Sonanta, and a couple Scott Joplin pieces in the works for my senior recital in about a year. It's some hard stuff, but it's fun.
