For more casual but still nice you could try Quigleys Pharmacy (Tonic). They are on Opentable.

How about Blue Duck Tavern or Ris?

I work on that corner. Definitely recommend District Commons. Founding Farmers is also nice but District Commons is better. Prima Piatti has been hit and miss in my estimation although I gather lunch is better than dinner. Circle Bistro at One Washington Circle is also nice.

If you are willing to walk a few blocks, Westend Bistro (23rd & M) is absolutely fantastic.

There's no Silver Diner here. Maybe you are thinking of Johnny Rockets?

The FF preacher aside, Kinkead's is always listed at a top DC spot. It's a lively lunch crowd and not speedy. I always like it. And there's always Prima Piatti and Prime Rib. But usually you'll see me at the Bread Line or the new Whole Foods. I'll have to check out the Bobby Flay's Burger.

Roti is similar to Chipotle or Panera. Its fast casual.

is roti any good?

Founding farmers or District Commons only. The rest are crap. But if you want a nice lunch with good service District Commons is your only option.

2000 Penn has Kinkead's, Bertucci's, Au Bon Pain and Johnny Rockets.

Aroma Indian and Primi Piatti are near 20th and Eye. Bobby Flay's Burger Palace at 21st and K.

District Commons at 2200 Penn.

Yeah, that area is kind of a waste land, your options are Founding Farmers and Silver Diner!

Founding Farmers?

How far are you willing to walk, OP? Maybe Circa?

date lunch?

hard pressed to think of anything over there...