Washington DC
I am extremely biased as I am from Washington, but I highly recommend it!! There is an absolute treasure trove of museums, galleries, great restaurants, great nightlife in Adams Morgan and Georgetown. It has more of a small town feel, as there is no industry there - except for the government! There are many parks, etc, and itis only a short drive to the Blue Ridge Parkway, the Eastern Shore/Baltimore, etc.
There is a lovely Jury's hotel at Dupont Circle - very central - near all of the embassies.
Enjoy!