Hi everyone,
My initial thought was indeed to rent a car and leave it at the airport before going to the hotel. Then the Uber solution was suggested
I think I won't know the solution I'll pick until the very last moment. I have a connection at JFK of 1.5h (from Europe) and fear about missing the flight to DCA in case of long TSA lane or if the boarder agents take me for few more questions (I have both euro and middle east eastern nationality).
Anyway I'll pick a flex option for the car in case of late arrival (or bad weather conditions). As some people said here the metro seems to be a coin flip and even it's a cheap option public transportation is always a risk (I leave in Paris

).
My main concern on Uber was beeing able to quickly find one near remote places but given your comments that is not an issue here so it is still open for me.
Thanks again