I have relocated relatively recently to the DC area for work and have noticed that being an AA FFer based in the area basically means being based at JFK or ORD. There are tons of DCA-JFK-DCA flights on Eagle every day, so it is very easy to hop up to JFK and catch flights wherever you need to go. JFK is generally better than ORD for WX delays, although I hear that ATC delays are getting better at ORD thanks to the opening of the new runway.

So, again, I think it's entirely doable to be an AA FFer based out of DCA, but you should expect to add another hour to travel days so that you can be "based" out of JFK (to allow for the Eagle segments).