Take the direct flight IAD-rdu. You are just getting off a xx hr flight.

I have forgotten if dec 24 is an extra busy day or an extra quite day, but it is not a normal day. in either case, the flights will be full and have bumping, and long lines because all is screwed up, or be canceled for weather/mech(low load) and lines will be long because all is screwed up.

The only good thing about taxi on dec. 24 is that I think traffic will be light, so you could get to dca in under an hour, and to bwi in about 1.5 hrs. You arrive at 6, get out of iad at 7or 730, and get to bwi at 9. you could not book a plane before 11 and have a high confidence factor of getting on the thing if that is an extra busy day.