I'm in Herndon as well - There's a subway on the intersection of Herndon Parkway and Elden Street. There's also a 5 guys in there for some decent, cheap burgers.
You have 2 costco's at just about the same distance from each other. I make my choice based on traffic and time of day. 28 north to Sterling or 28 south to Chantilly. Both locations are relatively new so you can't really go wrong choosing either one.
Katie brought up frozen chicken breasts, but I don't reccomend the unseasoned ones from costco, they tend to have an odd taste in my opinion. Jliao hit it on the head with the flavored ones. They go great with rice, in salads, and make decent sandwiches and you can buy them by the bagfull. Costco also sells cheap pasta and you can get any variety of sauces to put on them.
When all else fails, I can live off mac & cheese or Korean noodles.... god I love korean noodle bowls. ...
Chipotle is right off Elden as well. If you head torwards the toll road, past the chipotle you'll hit the clock tower (as its' aptly called). There you have a few decent, small restaurants, baja fresh, sub shop. Advance auto and starbucks also have shops there.
Best sushi in the area is in reston town center at Obi Sushi. Damn good spicy tuna rolls. There are a few places to drink there as well, rio grande, tap room, etc.
Which compex did you move into?