Gigi, I work in Dupont Circle. It's a heavenly place to shop, eat. I recommend staying at The Madison. It's reasonably priced for a bit of opulence and not chain-feeling.
For funsies, I do like the trolley tours that go to Arlington, all the monuments, shyt like that.
To eat:
Russia House
Levantes (greek)
Citronelle (if you're rich)
Blue Duck Tavern
Lavandou
La Chaumiere (again, if you're rich)

Shopping...one word: Georgetown. Spend as much time as you can there, I like to stalk the house Jackie Kennedy used to live in.

Visit the Embessies. As many as you can!

So much to do...I can send you a message with a complete itinerary if you want cuz I'm Type A like that.