Flying operationally engrained two things. ALWAYS have a light ON YOU, and know where the exits, structure, and be able to get there.
I usually put a light in my carry on while going through security then put it in my pocket while airborne. As much as I'd like to also have a multi-tool too, that isn't happening now.
As far as in DC, it depends on where your headed. Are you staying in DC proper or headed soemwhere else? Which airport are you going into? The area around Dulles isn'd bad, I'm up there all the time for work. National has a few decent places close in but pretty much sucks after about 6PM. Traffic BLOWS. The Beltway can be a bit confusing but look on the bright side, if you miss your exit it will come back around eventually.