From your experience I'm guessing you've already learned Pachelbel's Canon, but if not always a classic. I'm a big fan of Maple leaf rag if you're into the old time saloon feel.
Also if you're a FF geek this page is awesome,
Final Fantasy sheet music, not exactly stuff you can play for an audience or anything but if you're just learning for personal enjoyment I really like playing some of those. Suteki Da Ne and Aerith's theme are two I particularly enjoy.