Sunday a.m. before 10. Usually no traffic. If there's a route you can take to come from the north side, i.e, through Maryland, take it. You will bypass the DC Beltway but will be on the Baltimore Beltway which is far easier. I have driven the beltway many times in cars, truck w/pop-up, truck w/5'er and Class C with toad. Just go a little slower and watch the signs. Maybe it's because I've driven near/in Boston for so long I think people have a tendency to overreact about how bad the DC area is.
I don't believe you even can drive an RV through downtown (at least not on purpose!). I think there are posted restrictions.
Where from the south are you coming from?
