Baynesjp,
When you go is there anywhere to park your bike down by the National Mall area. Trying to figure out if I am going or not. We will end up camping some where outside of Arlington but if I can't park my bike anywhere near there I probably wont go.
There will be plenty of parking. I've done Run for the Wall twice and there's a huge field just north of the Lincoln Memorial (@23rd street and Constitution Ave) where all the Pre-Rolling Thunder parking happens. I never did the actual Rolling Thunder part of the ride, but understand there to be plenty of parking for that as well. From that parking area is easy access to all the memorials in that area as well.
If you can make run for the wall I highly encourage that as well. All "FNGs" usually get an opportunity to ride into Arlington National Cemetery as a group. It really depends on how far you ride with the group as they give preference to those that rode farther. In both cases I've still seen them offering the chance as far east as Hurricane, WV. RFTW is the ONLY group allowed to do this because they have consistently maintained a level of order and proper respect for the area. In addition there are several areas around arlington that RFTW has access to for camping, including indoors at one of the churches there. That's where I stayed both times.
Whatever you decide to do, have fun at it! Just watch out for all the one way/blocked streets and other issues that come with being in the capitol.