Good grub near Vienna
Bazin's on Church Street right in town. A bit pricey, but terrific food, atmosphere and bar (with full menu). Nothing else like it in town.
Tequilla Grande has decent Mexican.
Amphora Diner for late night dining (open 24 hours), it's an institution.
Haven't been but I'm told Foster's burger joint is good.
Vienna Italian Deli
All yummy and not expensive:
Sunflower Vegetarian Restaurant (on Route 123): Asian-style vegetarian fare
Panjshir II (Route 123): Afghan cuisine, a genuine mom-and-pop place
Shamshiry (just off of Route 7, close to Tyson's): Kabobs (every time I'm there, I'm one of the only non-Persians)
Tachibana (in McLean): Japanese, considered by many to be some of the best (and not terribly expensive) sushi in the area
Hope this helps.