I highly recommend using the W&OD. The trail is 2 miles shorter for me vs. taking roads. Check the W&OD maps to make sure you know the way through Falls Church. It uses side streets at times, and you want to make sure you pick up the trail when it reappears (like at Virginia Ave. after crossing I66).

Cars will even stop for you at the uncontrolled intersections at Cedar Lane, Hunter Mill and Sunset Hills.