I'm strongly in favor of the Ethiopian places around Adams Morgan, and Asylum for $.50 tacos and $2 Shiner Bocks during happy hour. And definitely give Mark's Kitchen another go. Old downtown Takoma Park is nifty, good Farmer's Market on Sundays, awesome video store. No bike parking, though. What gives, hippies?!
Be not afraid of Silver Spring. Avoid the craptastic "Silver Sprung" corporo-develoblock with it's various "Grilles" (the private garage there wouldn't put in bike racks because they didn't want to discourage anyone from driving) and hit places off Georgia Av and Colesville Rd. There's a huge variety of different restaurants around there--Cuban, Jamaican, Mexican, Burmese, Vietnamese, +more--all pretty cheap and all pretty good. Also AFI (old movies!) and Roundhouse Theatre (under 30-y-o, $10 to any show, criminally underpromoted).
DC's got a pretty ridiculous network of official groups for whatever interest you have (hang out in Adams Morgan enough and you'll see the WAKA people, for example), and being the bike organization, the Wash. Area Bicycle Association is well organized and helpful. They're throwing a swap meet this Saturday morning at the Bicycle Place 8313 Grubb Rd. Silver Spring.
Speaking of shops, you might be near Mt. Airy (College Park Bicycles) depending on where you are in T.P. People say they've got some good track stuff, but also high prices and loads of attitude. City Bikes is nice but pricey, as is Revolution. Chain Reaction is bare bones, but a pretty awesome organization with some really helpful people working there.
I live near Takoma, and I was scared of the biking distances at first. Then I got a bike and my life here got way better. The hill is 7 miles away, U district 3 or 4, Adams Morgan and Dupont 4 or 5. Easy.