IAD is probably the cheapest large airport we goto. Seriously compare it to BWI.I second Jhugz you can get the metro to downtown pretty easy from GAI. JYO is way out but a nice area with lots of things to do, And IAD to me is to expensive
LOLIf you go into GAI, do yourself a favor and MEL your TCAS. All the training activity around there scares the crap out of me every time I go.