Congrats on IAD!!!...my "home" international airport of choice, it's a great airport with a lot of buzz going on (fairly new tower, 3rd parallel runway under construction, the never ending battle of extending the metro out that way, those iconic mobile lounges going away in favor of an interterminal train, etc). As the airport encompasses a very metro area, you'll have a lot of options in terms of where to live... inside the beltway will be more expensive than outside for the most part, depending on where you choose commuting can become an issue based on the direction your coming from to reach the Dulles toll road...let me know if you have any specific questions.