I don't know about steepness on 81. I visit clients up there (blacksburg, VA) every couple months or so (from Virginia Beach, VA) and have taken a diesel westy up there once. Lost the main oil seal, but made it back. Steepest part is Afton Mountain near Charlottsville on I64. It's steep, but the real risk is low visibility. Drive carefully and pay attention! An alternative is to take 81 to 460 down to 95 then to NC. Slower, but few trucks and nice scenery.

For heading down the east coast, 95 is fastest but there are many other options (17 or 1 come to mind) each are SLOW.

john