People really need to get over this belief that IAD should be the biggest jewel on the crown. Who gives a f#@% if it's the international gateway to Washington?! Very few people from abroad go to Washington unless they have to. NYC on the other hand....
IAH is the largest hub in the system, and IAD isn't. Terminal B at IAH needs a serious update. C/D at IAD needs to be torn down and a new terminal built in its place. Which would be less time consuming to accomplish?
My "prediction" for the new UA operated by Continental is that EWR, SFO, and IAH will be their key strategic hubs. Then I would put ORD at the 4th spot. Then IAD (but hey, at least it's in better shape than CLE!!!).