What's wrong with driving in the city? Granted it isn't as much fun as Boston or Manhattan, but it'll do in a pinch.
Driving has always been bad into and out of DC and the suburb-to-suburb commute is the worst I've seen anywhere. Northern Virginia is blocked solid.
My previous job had a tech center in Manassas and a computer center down in Culpeper. I learned that no matter what time I left to drive back to NYC, it would be 7 or 8pm before I got to I95 on the Beltway. (Even tried circling around through Leesburg to the Point of Rocks bridge and up US 15. Nope.)
When my dad worked at Bennings Power Plant, PEPCO started every shift an hour or two ahead of the Federal government. Day-work was something like 7am to 3pm, and "4 - 12" was actually 3-to-11.
The Metro is the most reasonable solution. Just run the trains an hour or two later, and enlarge the entrances at the Navy Yard.