i do this trip at least monthly, if not twice a month
of all the suggestions, (metro, taxi, friend picking you up, VRE, etc) i can offer this wisdom i've gained
please do not lose sight of how simple and convenient UBER can be, it's cheap, efficient, no waiting, and you can get picked up right at the ramp of the any of the 3 airports in the FRZ
Having said that, I don't like the handful of times that i've had poor weather, be it wind, low ceilings, rain, or just night time limiting my options at the airports, I now pay the extra few dollars to land at dulles and use uber from there, it's so much easier, stress free, and great to know you have a fully lit 10,000ft runway to land/depart from, i find my door to door time is actually shorter than using college park or leesburg and my primary destination is near the pentagon