Ideas of where to solo travel in the eastern U.S.

Im looking to travel somewhere by myself for my birthday in January. I was looking at taking a couple of days to just explore an area in the United States. At first, I really wanted to travel to Chicago, but realized it would be too cold to do anything outside. I would prefer to stay somewhere that is max 3 hours in a plane and open to suggestions that are on the Amtrak line. For reference, I live in Durham, North Carolina. I was thinking maybe D.C, or somewhere further south? Im open to any ideas!!

Author: Serious_Can8263