Getting around Washington DC is best via the Metro or other mass transit. Car travel while convenient also comes with things like parking issues. Parking is free at the Conference center and hotels. Need to rent a car? Find information here.
The metro is connected at the Wiehle- Reston Station. The station is 9.5 miles by car/taxi/uber/lyft from the Executive Conference & Training Center and will take you right into downtown DC.
One attraction very near the Conference site is the Smithsonian Air & Space Museum which is just 6.5 miles from the Conference site.
Other sight seeing opportunities abound- (Washington DC)