re: Parking in Washington DC

I lived in Fairfax near George Mason. You've got options. The orange line terminus is Vienna, near western/northern areas of Fairfax. Franconia-Springfield is the terminus of the blue line; distance wise we lived halfway between but always took the blue line to avoid driving through the Fairfax downtown area.

You can also drive closer and take the metro nearer to the city; Falls Church East is the last metro stop on the orange line (heading towards DC) that has a parking lot if I recall correctly. You can also take a bus into the pentagon (all metro trains and buses accept the smartrip card, which I highly suggest you purchase if taking public trans). The pentagon serves as a trans hub and you can take the metro from there into DC.

I suggest looking at where you're going to be in Fairfax and use the wmata website Metro DC to get a better idea.

Hope that helps.