I think Graffiato is overpriced and not that great. And it's mostly business types so not fun for that age group. I'd go with Matchbox, Carmines or Clyde's. Austin Grill or Jaleo would be fun too. And finish the meal with a cupcake from Red Velvet!

Jaleo! Short walk, fun, reliably great food. My 12-year-old's favorite restaurant.

Zatinya! Awesome.

Daikaya for either ramen on first floor or izakaya on second floor, though they might not be open for lunch.

How about Austin Grill?

I think Zaytinya is a bit boring for teens.
Oya might be nice. Or Oyamel, completely different places btw.

Thanks all, for the great suggestions! Vapianos, Shake Shack and Five Guys are, of course, very popular with kids this age, but I was looking for something with table service. The lunch is a surprise reward for working all summer on a community service project, so I want it to feel like a special occasion. I've taken my high school DD and her friends to Ping Pong Dim Sum in Dupont Circle for a birthday celebration and that was a big hit, but I'd forgotten about the Verizon Center location. That would be a great option. Hill Country is also a favorite with my kids and the pop-up will be serving in the museum courtyard, but I'm worried about the weather being too hot. I love Zaytinya and hadn't thought of that either, but I think it could work. I was considering Graffiato too, though I haven't been there myself, and am glad to hear others suggest it. I'll check out the other recommendations as well. Again, thanks.