The one I do is all ride levels leaving from Belle Haven Marina on the MVT @ 5:45. The ride is sponsored by Wheel Nuts in Old Town.
Runs 18-25 miles of hills.
Its a good group of people to ride in one of the only areas (I’ve seen) inside the Beltway that has very low vehicle traffic. Repetitive hills and some flats, it’s overall a decent course for all pace levels.