I live in Alexandria and commute to Falls Church — in fact I work in the same building with OTSG. I'll be sure to look out for you if that's where you're going to be!
The great thing about northern Virginia is there aren't really many "bad" places to live. There are some seedy pockets here and there, but overall, almost anywhere will be livable.
You can still find some affordable places in Alexandria or Springfield, but by "affordable," I mean maybe you'd find a place under a half-million. Maybe. The commute from there is a straight 10-12 mile shot around the Beltway, and it rarely gets too soul-sucking.
And, the closest Metro stop to that office building is about a mile and a half away, but they run shuttles to the stop. They also run shuttles to the Pentagon, so you could take Metro there instead, which is easier if you're coming from the south.
The western suburbs might be worth a look too, like Reston, Chantilly and Haymarket. You'd be driving in on 66, but getting off before you get inside the Beltway where it gets crazy. Metro goes pretty far west now, and stops in Ashburn, which is a few miles past Dulles.
Fairfax County schools are fine as long as you don't need anything other than the bare minimum from them.
I tried to PM you and the site didn't let me, but drop me a line if you want to know more specifics.