So you're just staying at Dulles that night. Would have helped to include that info. Also a bit more as to your interests and how far you're willing to drive. A full day's drive from DC (not in DC) and then to Dulles potentially covers a huge amount of territory. If it's a weekday, still need to account for rush hour traffic, especially if needing to go back through DC to get to Dulles (e.g., if you go to Annapolis). If you want history and scenery, I'd consider Harper's Ferry, Winchester, Shenandoah Natl. Park, Frederick or Gettysburg. None of which would require cutting back through DC to get to Dulles, especially if you use the Greenway.