Awesome! How are you feeling at 6 mos pregnant? My ideal right now would be a morning run, bike ride, or hike, followed by a drawn out brunch/lunch at St Anselm, Le Diplomate, or Stable, followed by a visit to the Hirshorn or another gallery, then a nice dinner.
Other options: rent a boat or kayaks in Georgetown and go out on the water; go to SpaWorld (or a nice hotel if SpaWorld is not your thing) and get massages; see an interesting movie at E street cinema or the Angelica