Public transportation offers many options. Metrobus schedules are available online and there are many routes to Washington, D.C., Tysons, Falls Church and locations west along with close in neighboring areas. The Metrorail is located in Vienna, just right "down the street" from Oakton on Chain Bridge Road, which becomes Maple Avenue in Vienna, then a right turn on Nutley Avenue takes you to the Metro station. The Silver Line is coming to Reston later this year. There are also many special stops for buses to the Pentagon and other key Washington locations.
I hope you're able to find just what you need and if you're new to the area, Welcome!
Best regards, Sherry