Just curious. Is it less hilly to travel 460/19 then to Abingdon and hit I81. or is it better to stay on I77 to 81S towards Knoxville. Pulling a 30 ft TT
From I-77, I-81 is fairly flat to gently rolling, no real big grades all the way to K'ville. Haven't been on the other route you are considering. Personally, I like going the secondary roads rather than the interstates when time is no concern.