Tech, don't be fooled by the driving time that you receive from Google maps, etc. When you leave I-75 and head SSW on 461, 90, etc. you are destined for good roads, and lots of small towns. And it will be like that the entire way. There are probably 12-15 towns in that stretch, every one with a caution light, traffic light, 30 MPH speed limit and school zone. I don't believe there is anything wrong with the highways, but this is far from interstate quality travelling. If you're in a hurry, follow the interstate system. If you're wanting to actually see something then get off that infernal concrete ribbon and live a little. (Oops, I snuck personal opinion in there
)
Have a great time while you're there and spend lots of money! Tennessee needs your tourist dollars!