Hey, I did a lot of biking in Knoxville. Of course, that was in the 1960s when I was in college at UT.

You definitely want a hybrid and you want low gears -- a beach cruiser or comfort bike will make it too hard to explore those beautiful hills. I live in NYC (mostly flat) and I'm glad for my granny gears.

I did luck out on a used Trek -- bought it from a bike rental place. I agree with the caveats about Craigslist, though it's worth checking.

Good luck!