Cherry Hill is a great park from what I've been told. It also has the best access to the public transit system in DC (the Metro). There is a bus stop right outside of its gates that takes you to the train station which takes you into and around the city. If I'm going into the city in the day time, its what I take. Cherry Hill also has the amenities that you'd want- pool, laundry, full hookups, etc. BUT- it's literally at the juncture of I-95 and I-495 (the DC Beltway) and its priced according to its convenience to the city and amenities.
There is a national park called Greenbelt National Park
. This is going to be a bit more rustic of camping with less (no?) hookups. Still convenient- likely a bus, but probably easier to drive to a metro stop (either Greenbelt or a little further to New Carrollton which has better parking IMO and is more convenient for the Smithsonian).
A little further out to the north is the Capitol KOA
. This is going to be a good 30+ minute drive to get to the city. Full amenities, slightly less "right on the highway" as Cherry Hill.
A little further to the south is Duncan Family Campground
. Never stayed and don't know much- but people who have stayed like it. Looks like you could drive and park at the Largo Town Center metro stop.
A bit to the west in northern Virginia is a Bull Run Campground
. You'll have to drive 20 minutes or so to the Vienna metro stop, but this was surprisingly a beautiful campground (that also happens to be big rig friendly- not your need, I know but useful for me
). I stayed here for work in Fairfax. They have a neat pool/waterpark that my wife and kids enjoyed.
There's also the nudist place outside of Annapolis (link
). Not sure about public transit- I'd likely just drive to New Carrollton from here.
The WMATA public transit page is:
Metro - Home page
There are day passes available that let you get onto and off of the train as needed. I'm not sure if that includes the buses. Otherwise, there are plenty of tours. One neat thing would be to rent kayaks from the Key Bridge Boathouse
and paddle up towards the monuments.