(Continued in comments!) A little about DC.... Northwest DC is the nicest quadrant, specifically ALL areas west of Rock Creek Park. If you look at a map, you can see Rock Creek and the big green park area. Almost without exception, this is the safest part of the city. It is very liberal, Democrat, whatever- but serious street crime is pretty much nonexistent. There are few motels in NW I would not recommend or consider dangerous. Upper Georgia Ave, 5500 block and up has a few, but it's still safer than much of the rest of the city.
The New York Ave corridor (US Route 50) has a lot of motels but it is sketchy. Lots of people are permanent residents those motels and probably a lot of the drugs and shit we'd all like to avoid.
Arlington and Alexandria City are nice. Motels are decent, but maybe a little pricey in Crystal City, Rosslyn and Clarendon. These areas are a 10 to 15 minute drive across the river to downtown. 10 to 15 minutes further west there is a strip of motels on Arlington Blvd (Rt 50) in Falls Church. Safe area. Stop in Eden Center which is a nearby Vietnamese shopping center with about 2 dozen good restaurants. Most of the peeps there are supporters.
Tysons Corner hotels are a little pricier, but a safe bet.
AVOID- The eastern DC suburbs in Prince Georges County, Maryland aren't great, College Park, Hyattsville, Landover, Suitland have a lot of hoody areas. The one exception is National Harbor, where CPAC was held.
The northwestern suburbs of DC in Montgomery County, MD are mostly safe. Some public housing and a lot of libs, but no one should feel threatened there at all.
If you are coming in a camper or RV:
From the west- there are Walmarts about 30 to 40 minutes out of town where you can park overnight. Manassas, Gainesville, Fair Oaks, Fairfax City are all very safe places. You will probably be received well in the first two; the second two are more Dem but not places I would feel threatened.
From the north- if you are coming down from NY/NJ/PA/New England there is a rest stop in Jessup, MD where you can post up and camp. Technically, only supposed to be 2 hrs but this is rarely enforced, if is, it will be by MD State Police.and I've never heard them force a driver who needed a nap to drive... There are Walmarts off the 95 corridor, but the neighborhoods not as nice. The Walmart in Landover HIlls is one I would AVOID, as well as any of the ones in DC, which do not have much parking. There is a campground/RV park in Greenbelt, MD, not sure if still open but it's an easy 30 minute drive to downtown DC from there...
From the south- If you are coming up 95 from Carolinas, FL, GA etc look for the Walmarts in Kingstowne (best) and Alexandria (Richmond Hwy). Also some industrial parks where no one is going to bother you in Lorton, Shirley/Edsall Road, Ravensworh (Braddock Rd in Springfield). There are some other places to be left alone on Wheeler Ave and Eisenhower Ave in Alexandria City. Basically places that are active in the day, but then shut down after dark, No one will mess with you there.