On that note, to get from IAD to DCA:

Take the Washington Flyer bus from IAD to the West Falls Church Metro station. Catch it at the upper level. IIRC it runs every 30 minutes and costs $4 one way for uniformed crew. Then catch the Metro to DCA. You will have to change trains once. Googling the DC Metro will give you the route map.

If you hit everything just right, total time from IAD to DCA is about 40 minutes, but it can take up to an hour or more.

DCA to CLT can be tough also. The second jumpseat on the Airbus saved my bacon more than once.

This is getting complicated, eh? Drive to ROA. If you get out, good. If not, it is about a 2 1/2 hour drive to CLT. If you can't get out of CLT to ROA, go in with the other SA's on a rental car.