Reston Town Center is a modern, planned development. It's a lot better done than many other lifestyle centers. The buildings are tall enough that you do feel like you're in a city. Not a big one (the site is about 4x5 blocks).
But yes, you can live, work, and play in one spot. There's companies, like Comscore, Oracle, and Microsoft. There's condos that you can live in. There are some clothes stores, cafes and restaurants, and a skating rink for the winter.