There's a new shop called The Bike Rack (www.bikerackdc.com) on 14th and Q which seems to cater to a fixie crowd, so you'll want to check that out, though I also reccomend Bicycle Pro Shop in Georgetown on M street across from the Key Bridge for pure bike porn and really friendly people. Adams Morgan has some good little food joints and two punk rock record stores (Smash and Crooked Beats), so bring some bucks for some that. There's a whole bunch of little eateries in Georgetown and on the U street corridor, but your day in DC will not be complete without a beer at the Brickskeller near DuPont Circle.

If you want flat, unninterupted miles, you can ride at Hains Point. Georgetown has fun little back alleys to play around in, including some nice cobbled stretches. It's also fun to play around by the National Mall and in Downtown, which should be relatively empty as most businesses will be closed. DuPont circle is also a neat little place to ride and eat.

Good luck and enjoy your visit.