Check out the beautiful and fascinating collections at the Freer/Sackler Gallery of Art on the downtown mall. Betsy volunteers a few times each month at this museum, which is dedicated to Asian art and is a part of the world-renowned Smithsonian Institution.
Spend some time in the Navy Yard neighborhood of DC, a favorite of Betsy and Rob. Located right next to Nationals Park, you can find good food at Rasa (Indian fast casual) or at Osteria Morini (Italian). Check out the rooftop patio at District Winery for a great view.
Venture into the heart of DC to check out the Logan Circle and Dupont Circle neighborhood. Learn from captivating exhibits that regularly rotate at the National Geographic Museum, or find an interesting book and some dessert at Kramerbooks & Afterthoughts Cafe, a local institution. If you're thirsty, head over to ChurchKey (perhaps the best beer bar in DC) or McClellan's Retreat (go for the excellent Civil War pun, stay for the even better cocktails).