7th st also has a cupcake place and the small Clara Barton museum (which I think is pay what you want-- interesting Civil War history site)

Don't go to any restaurant that's right at the Capitol One Arena.

This is such a great area. You will be within walking distance of the White House, the Washington Monument, the Capitol Building, the Natural History Museum, the American History Museum, the American Indian Museum, the Air and Space Museum. If you want to pay, there if the Spy Museum. You will have too many things to do. Have fun.

The Building Museum isn't far. They have some cool stuff. There's also high street type shopping and lots of restaurant options (Jaleo, Zaytinya, e.g.).

There's a ton. Smithsonian American Art Museum and Renwick Gallery (in the same building, separated by a beautiful courtyard) is across from Capital One Arena.
https://americanart.si.edu/

Chinatown has good restaurants-I like Tony Cheng's on H. Clyde's is next door to Cap One. The Shakespeare Theatre is across the street on the other side. Sixth and I Synagogue.

Spy Museum is not far from the arena, either. Unlike the Portrait Gallery, it costs to get in, but many kids like it more.

There are plenty of options. A lot of chain restaurants like Nando's, Green Turtle, Legal Seafood, Shake Shake. There's a Matchbox on H St. Further down 7th is Hill Country. There are some good, more expensive restaurants on 6th.

Depending on how early you get there, you might head over to the Building Museum or the Portrait Gallery for a bit.

Going to a Wizards game this Friday and will be driving into the city a few hours early. Need a place to kill time with my 13 year old daughter.