When I was an Examiner, we lived in Fairfax... the commute was very manageable when I drove to PTO at 5 a.m., and returned home at 2:30 or 3:00 -- new Examiner's will get that flexibility after about 4-6 months, although it depends on SPE.
Living in DC is best thought of as metro stops, not cities. PTO is on the yellow/blue line, I think the stop is "King st."? in alexandria. So if you live near a yellow/blue line metro stop, you won't have to transfer.
When I took metro, I had to drive to Vienna stop (orange line), and go from there. That was a 90 minute commute during general rush hour and that was after I figured out shortcuts how to get to metro station.