The Cumberland Gap
-- From Kentucky, through Tennessee, and into Virginia

I just drove this one in April of 1997. In Kentucky, get off of I-75 at exit #29, (US25E). Take 25E all the way to the state border. It is 4 lane highway all the way, with some fun hills.
At the border, you will find the new Cumberland Gap Tunnel! Its about a mile long, and two lanes each direction. Its pretty amazing looking!
Once you are through the tunnel, take an immediate exit to go to US 58. The Virginia border is only about a mile away here. Note that radar detectors are illegal in Virginia, so if you have one, take it and put it in the glovebox or somewhere else out of sight.
Then take US58 all the way to Bristol, VA. This road is mostly 4 lane, but that are some great sections that are 2 lanes in Virginia, especially the last 30 miles before Bristol. I found out that even the local residents don't drive on US58, but its made for the MR2! And when you get to Bristol, you can go tothe NASCAR races at the local track.