Just an FYI, taxes are higher in DC. So, you would be paying more in DC income tax than you would Maryland or Virginia income tax. In Virginia, there is personal property tax, so you get taxed on your car every year, not just the sales tax when you buy it.
About Maryland, Prince George County is okay. It costs less to live there than in Montgomery County because, well, it's a bit more ghetto. It used to have a high auto theft crime rate. I don't know if it is still like that. More about Montgomery County Maryland, downtown Silver Spring isn't really safe. I would say Wheaton and all points north and north west is better. Rockville, Gaithersburg, Germantown, Urbana and some people even commute in from Frederick. Columbia is its own mini-city and is expensive but nice. It's also half-way to Baltimore.
I don't know much about the Virginia side since I didn't live there. Suburban sprawl in VA goes west and south. People commute in from Leesburg, Centerville, Manassas, Reston, Woodbridge and Fredericksburg to DC daily. It's crazy.
Traffic is crazy, so that is why those who work inside the Beltway choose to live inside the Beltway.