Sushi Taro located at 17th and P St NW. I’ve heard it called the "Mortons" of sushi places. Make no mistake it is wonderful. Reservation is highly suggested. Atmosphere is wonderful. They welcome you and there is no rush. The best seat of course is to get a spot right at the sushi bar. Hard to come by though. They offer traditional Japanese style seating (on the floor) as well.
Each Spring they have an annual "all you can eat" Cherry Blossom Festival celebration and the line goes down the block with people waiting for hours.
You can’t go wrong going here, just make a reservation or go early. Read more about the sushi choices.