Well so far the longest I've played is the Silent Death song at 11 minutes. That was fun. Ha.
Anywho, I've been looking to play Beethoven's Moonlight Sonata. All three movements. Its going to start out boring but I'll love the third movement. Its just so great, despite how old that piece is it still so intense.
Oh, and I adore Rhapsody In Blue. I'll probably play that at some point.
And someone mentioned Beethoven's Ninth. That'd be fantastic to play at some point.
And what is the length limit of the song? Its kind of a shame.