Have you considered NE, but further afield? We've always wanted to go to Nova Scotia, from SC it would be about a 3,000 loop, depending on what other stops you made. You could stop in Washington DC for the history ... and/or Philadelphia, then make stops in New Hampshire & Vermont if you want, but spend most of your time exploring Maine & north to Nova Scotia. That trip's on our bucket list, except we'll leave from Illinois.
We just returned from a 5300 mile loop from Illinois up through SD, ND to Glacier, Yellowstone & Grand Tetons, back through Denver & back to Illinois - so we feel your pain about trying to plan another LONG road trip. :)
Having spent several months living in Guatemala, it's a different sort of adventure, but adventure for sure. If you go, don't miss Lake Atitlan, Tikal (Mayan Ruins), Antigua ... I could go on & on, but I'm sure your college buddy knows more. :)
ENJOY!
