Any Chinese restaurant suggestions near 6th &I NW DC
Full Kee near 5th and I Sts.for Hing Kong Style. Go for the duck stuffed with shrimp paste, and the oyster and ginger casserole.
Full Kee is probably the best in "China Block" if you're looking for Cantonese style. In a pinch, you could do Eat First or Chinatown Express. I always went to Full Kee when I lived in DC as an intern (given that I didn't have a car to go to Rockville). Either way, it's slim pickings in Chinatown for non-American Chinese.
China Boy is a total dump. One table, bulletproof glass, specials in Chinese on the wall. Excellent chow foon. You can kill yourself for $10 in there.
My favorite Chinese places in the area are in the burbs unfortunately.
For around 6th/I:
I don't like Eat First. I'm ok with Chinatown Express and Chinatown Garden. They aren't amazing, but they are serviceable.
I usually just get caught in the the Daikaya ramen tractor beam when I'm around there lately, but that isn't Chinese.
I've always been a fan of New Big Wong. The house special "vegetables and squid in the king" or something like that, the salt and pepper baby squid heads with cashews, the da pang fried rice noodles, and the fried "good dale" (singapore style chow fun) are eternal favorites.
They do many other things well, such as the conch or frog (your choice) with sugar snap peas which is amongst the Chinese language specials on the wall.