Best time to make it through Washinton DC?

Since you can't use the tunnels through Baltimore anyway, I would take 695 to Key Bridge then switch to 97S. This takes you to 50/301 near Annapolis. Get on 50/301 going west, then onto 301S. You can ride that all to the way to Bowling Green where you take the Bowling Green Bypass to 95S. You could stay on 301 but whenever I do, I get stuck behind a little old lady in a 1966 oldsmobile or an old man with a hat in a 1950 pickup truck (it is one lane each way through small towns).

I would also recommend taking 295 over 95S. The speed limit is faster, the road is in better condition, the drivers are less crazy, and it is only 5 miles or so longer.