Some of the nicer restaurants in Tyson's Corner are only open for dinner on weekends (2941, Colvin Run, etc.).
Cafe Deluxe should work for you. Not great, but consistently good.
Clyde's is another local spot. I like Deluxe just a tad better.
If that doesn't sound good, there's a
Legal Seafoods outpost in the Galleria (the fancier) mall. I'm a huge fan of their ground tuna burger.
Too bad Vietnamese is a no-go. You're going to be super-close to what's arguably the best Vietnamese food in the U.S. not on the west coast.
Ronna