taylor gourmet takes the cake for me. that place is amazing.
the diner has always been a nice 4am spot, although admo sucks on the weekends.
taco impala on h st use to be pretty fantastic, they dissapeared tho i believe?
duccini's at 18th and u is on my late-night to-do list.  they have some nice seat-yourself patio benches, and are open till 5am.
agree w/ black and orange being meh.  i'll go back in a month and see if they step up there game.