Originally Posted by johnep1
If you won't have a car, BWI is better than IAD because the MARC train runs from BWI to Union Station in DC. No public transportation goes from DC to IAD.
It depends, not only on where in DC (as hbyerly notes), but on what schedule. The MARC train does not run on any weekends or holiday, and Amtrak is infrequent. There is hourly express bus service to both BWI (B30) and IAD (5A), but the 5A gets you much closer-- the B30 bus only goes to Greenbelt, the terminus of Metro's Green Line, whereas the 5A will put you in Rosslyn (in Arlington just across from Georgetown) or L'Enfant Plaza (2-3 stops below downtown). Of course, since it appears to be for work, the OP hopefully won't spend much time on either.
