I will be traveling to DC (actually, Bethesda) by train from NY City. I will have two meals on my own: One, around noon on Sunday the other a quite early dinner on Tuesday (my train is at 7).
I will be dining alone, but I do that a lot. But some restaurants might not like it.
I like all cuisines and am an adventurous eater. Some favorites are Thai, Korean, Sichuan, Italian, southern USA, barbecue, etc. but I will go with anything that's really good or special to the area. For the Sunday meal, I am more partial to lunch type meals than brunch - i.e. not a big fan of pancakes, French toast, eggs etc (although sausages and bacon are great!)
Cost - I don't want some hugely priced meal, but it doesn't need to be cheap.
Attire: I will be in khaki pants and a dress shirt, probably no jacket, definitely no tie.