Go to adams morgan, you have balcony dining at some nice, chill restaraunts, you have places like thryst which is a lounge/bar, very cool and casual for like a after dinner drink. Ruths Chris is also in adams morgan.

You have McCormick and Schmidt on K street...easy as all hell to find, go in on the 14th street bridge, follow 14th to K street, go left and look for it, don't remember exact cross street.

If you need any directions, all the way down to which streets are one way...PM me...I was a bike courier for 4 years.

Georgetown IMO is better suited for a daytime visit or bar hopping, not for being "romantic"