http://www.10best.com/Washington/Res...nch/index.html
http://www.findoutdc.com/brunch/index.shtml

Of these, I had brunch at Georgia Brown's, Cashion's Eat Place, Old Ebbitt Grill, and Seasons when I lived in DC. Each place on the two lists abive have their own ambiance (Adams Morgan vs. Political Scene vs. a Scenic View), and all 4 I went to had excellent food. The Smithsonian Castle is also a cool place for brunch in DC, as are some of the other government places (i.e. on the roof at the Kennedy Center, at the National Gallery of Art Terrace Cafe, etc). Sequoia is one of my favorite places in DC - go there for dinner one evening if the weather is nice.

For pure foodie appeal, the weekend lunch at Kinkead's is always good - though it is not a full brunch per se. My favorite place with an actual brunch menu is Kramerbooks and Afterwards Cafe in Dupont Circle. Not quite as upscale as most on the list, but really good food and a great place to people watch and be in the center of the city on a weekend morning. I think the brunch menu is offered Saturday too.