Just like any large metro area, it really depends on where you're working and how far you're willing to commute. Do not, under any circumstances, consider living south or west of DC more than ten miles if you're actually going to work in DC. Route 7, I-66, and I-95 are not fun commutes OTOH, East won't be as much of a problem. The school districts are county-wide, but of course each school will be different.