Yes, Tennessee has the best roads in the US!
As for I-75, just remember that there is no way to cross the Appalachians without some steep grades. I-75 is far from the worst and if I remember correctly the stretch coming down from Ohio to Georgia doesn't have any major short, steep grades like I-26, I-40 or I-77.
Now once you get past Macon, make sure and stay the heck out of the fast lane! I-75 has the fastest traffic I've seen anywhere...
2010 Flagstaff 829RGSS
Still to go: AK, NL, NT, NU, YT