Summit is actually three tracks: Main, Shenandoah, and Jefferson.
Jefferson is tiny and sucks (imo) but is a decent track to get your feet wet on.
Shenandoah is small and twisty although some people complain about the walls.
Main is hard to find weekend dates on but a great track where all the racing happens.
If you expand your reach slightly there are several more tracks:
BeaveRun (Wampum, PA) ~4.5 hours away from DC. Great track, tons of fun.
VIR (Danville, VA) ~4 hours from DC. Actually four tracks: Patriot, North, South, Full. Patriot sucks cack but the rest are good.
There is a new track opening in New Jersey in a couple months as well.