Much easier than with public transport.
We rented the DMV Cruiser from Vander Outdoors for 10 days. We extensively explored the beautiful Shenandoah National Park, and its beautiful hikes. Also the DC region and the banks of the Potomac River (with the many Bald Eagles).
The DMV Cruiser is a very nice campervan. Two adults, and our teenage son had more than enough space. The campervan is compact enough to park in any parking spot without worries, even just to explore Washington DC at your own pace. Much easier than with public transport.