D.C. remains one of our favorites. We usually fly in, do a day in Virginia Wine Country and then stay in the city in Dupont or Woodley Park. We usually go into IAD in the morning, so Wine Country comes first.

You could reverse the order of those: fly or train to Union Station or DCA, and then do a one-day in-town rental car if you want to go out to VA wine country. Or if wine isn't your thing, just enjoy the city...