I had some great tacos on MD 175 just off the Baltimore Washington Parkway. It was a food truck. It didn't look like much but I was hungry. They had a taco for $2.49. I ordered one. I paid for it and realized in the car that the Korean lady gave me three. I went back and told her and she said it was ok. Normally they are $5.99 for 3. I gave her another dollar because it was all I had.
They were delicious. The beef I think was the same she would use for the $5.99 Cheesesteak sandwich and that made the taco. It was dressed with lettuce, salsa and cabbage which gave it a nice crunch. She asked if I wanted jalapeno or hot sauce. I said "yes". Neither gave it much heat, if any, but there was a sweetness that I could have done without. But it kept me full for the rest of the afternoon.
They also have some Korean fair of which cannot remember the name but began with a "B". Platters run from $6.99-9.99.
Overall, I will make a specific stop there again.
Why limit yourself? If you are near 7th Street, you can easily walk two blocks to either the L'Enfant (south) or Archives (north) Metro stations and go to many places fairly quickly.
I think all of these suggestions are great. Even the ones with which I am not familiar.
Here are some additions.
If in Little Italy, I suggest La Scala. It is family friendly and has great food that they will prepare in nearly any fashion you desire. But don't miss the Grilled Caesar Salad. My wife remarked it tasted like steak but without the meat. http://www.lascaladining.com/
My other suggestion would be Kali's Mezze in Fells Point on Aliceanna St. It is Mediterranean tapas. Mmmmmm. Small plates with big flavor. http://www.kalismezze.com/ for the menu.
Enjoy your stay.