I arrive at IAD at ~7pm, and my flight KE to ICN flight is the following day at noon. I have never been to Washington, and I was hoping to see some of the sights (I know with the time I arrive there won't be much to see at night. Are there many 24 hour restaurants (I will happily play McRefugee until the daylight hours). Are there any suggestions of places I can camp out for the evening that would put me in a good place for a couple hours of sightseeing in the morning?

I am 20 and will only have a carry-on, so I don't have to worry about getting my bags robbed at 4am.