Have you ever considered using the Metro (subway)? One good thing about the DC area is it's one of the few places in the United States with a decent mass transit system. Even if it doesn't go to your town, you could park at the station in Maryland and ride it to Arlington -- thereby avoiding the hell known as DC highways.
The Metro may not be the height of safety either, but at least you have freedom of movement in a ****** scenario. And you'll never be stuck in traffic.
Also consider carrying a knife. At contact distance a knife is just as good as a gun if you know how to use it.