If you are heading North on 95 you won't be driving through downtown Wash D.C. 95 bears off, to the East, and goes around D.C. and eventually you will come to College Park, Maryland. Traffic is heavy during the morning rush and the evening escape.
Cherry Hill Park is a very nice campground. You can purchase tours right out of the campground, or you can go to the Metro Station and get dropped off right in the mall at the museums and monuments. There are plenty of other riders who will assist you with negotiating the Metro. It's really not that hard once you ride it a couple of times. There is a shuttle from the campground to get you to the Metro if you don't want to drive the couple of blocks.
The workers at Cherry Hill Park will help you figure things out.
Have a good time.
