Anita and I were looking for parking for our car in DC while we do the GAP trail from Pittsburgh back to DC. Found parking for $10 day at the Pentagon City Sheraton. Looks to be close to bike paths that will get us into DC to take AMTRAK to Pittsburgh. Book through the Parksleepfly.com website.
Also when booking with Amtrak the direct trains were all full (or the bike spots were all full, or Amtrak wasn't booking the bike spots) but were able to get to Pittsburg via Philly with a change of trains. Now hoping for nice weather.