Pick up a 'best of' album of J.S. Bach. You'll get a good sampling of a variety of his volumous output (his total works take up about 250 CDs--and we less than half of what he wrote), and you'll get a different musical perspective.

If you want to stick with 'rock', why not go back a bit to groups like The Who, The Rolling Stones, Led Zepellin, Jimmy Hendrix, etc.

"Dave Brubeck's Greatest Hits" is also a good CD good catchy music and also music that challenges you in its strucutre. (Ever listen to music that has a beat, but that you can't tap your foot or snap your to? No? Check out 'Unsquare Dance'.)

While I haven't purchased 'best of' CDs in a little while, they're a great way to get a gentle introduction to a new genre. Then, if you like some of the works, you can ask (either online or at the record store): 'I like this song, can you recommend other works that are in the same vein?'.