From one of your posts it looks like you are from the Philly area. If you want something closer to home check out this guys site Bikeable Brews It's for bike trails on in the DC area. He doesn't cover DC itself but there are at least 10 breweries in the District. Check out his Geospatial presentations and filter on Brewery. The W&OD has the majority of the breweries and is 40+ miles long. You can use the other trails to form a more varied trip. DC down the Mt Vernon to the W&OD. On the way back take the Custis trail back to the city. I have done this in many ways but I usually end up going out on the W&OD to Leesburg then crossing the river to the C&O Canal to camp. There are of course plenty of B&Bs and hotels if you prefer that route. It's all paved trails unless you end up going to the C&O. that is a little bit of road riding then dirt trail. gmap-pedometer.com You could also ride the canal back to the city if you have had enough beer and just want to take your time and camp.