I don't know much about the NoVA courses, since I live in Northeast and always seem to be headed north instead of south, so here's the MD courses, from closest to farthest:Calvert Park
is an 18 hole course in College Park, MD, just outside NE DC. It's mostly flat, and kind of small. But it's very well kept up, 3 concrete pads for each basket, and has enough trees to make it a good course. It's not the one you'll be blown away by, but it's a great course to get a fix and it's close. It's not far from the College Park Metro station, and you can play all 18 in less than an hour without having to run.
Also: it's right next to College Park Airport, which has a small museum. They used to have 10-15 discs in their gift shop, but I went in there just recently and they've got a whole wall, and at least one display stack of Wizards, and another of Rocs.
About 40 minutes up 95 towards Baltimore is Rockburn Branch Park
, which is an awesome 18 hole course, very challenging and gorgeous. This is the one I head for if I can carve out more than a couple hours on a weekend. It's more challenging now that we're into summer, as the grass is high off the open fairways and the shule is thick. The lost and found thread for Rockburn on the MD Disc Golf forum has been very active. This one's definitely worth playing if you can squeeze it in.
Up from there is Patapsco
(very challenging) and Druid Hill Park
in Baltimore (great course to play, always love this gem).
Northwest of DC up 270 is Seneca Creek
, which used to be an NT stop (now they just do A-tiers). It's also been expanded to 27 holes and has new pads. If you can carve out half a day or more, and you find yourself on the Maryland side, I think this is probably the course to spend it at. Unless having a beer between rounds is important, because you can't do that there anymore.