I live about 1/2 a mile from one of the Capitol City Brew Co locations (the Shirlington location), so I'm definitely a regular there, especially on Thursdays because they have $2 pints all day long and 1/2 price appetizers during Happy Hour. Their Amber Waves red ale is my favorite beer there. Unfortunately I haven't been to the Pizzeria place that's mentioned above, but I'll definitely have to check that place out sometime. Another place that usually has a decent selection of local brews on tap is Hardtimes Cafe... The location in College Park usually has something from Clipper City Brewery (Baltimore) and/or Flying Dog Brewery (Frederick, MD).
As for LHBS, I'm not aware of any in the city. Maryland Homebrew is in Columbia, MD which is about half way between DC and Baltimore, they have a pretty good selection and are always very nice and helpful. There's also a very small store that's closer to the city called myLHBS, it's in Falls Church, right across the street from a Dogfish Head Ale House, which would be much closer than driving to the Fairfax DFH.
PM me if you want directions to any of these places.
