There are Cars and Coffee nearby - There is one Sunday in Sterling at Dulles Landing. I've taken my 914/6 once or twice. I am about 10 min from U-H as well. Check as well for one at Intersport Performance in Ashburn Va (Just north of U-H). Not 914 centric, but Porsche centric. They've just opened this location and have had a few on Saturdays.
But if you are going to hit just "one" cars and coffee - it would be Katies (
https://oldbrogue.com/event/katies-cars-coffee/all/ ) , early Sat AM in Great Falls. Lots of monied folks and some nice old classics usually are in attendance.. Porsches, Lancias, Alfas, Ferraris, stately benzes etc. Its not california, but its how some get by
No real local PCA events - not til 3/22 and later (AX, and DE events)
As others mentioned, the U-H facility is fantastic. My son loves going there so we've been several times. $15-20 to "park", but then the exhibits are free... Downtown is nice too, but it feels cramped in comparison, but they have some nice stuff to check out.