Douglas J. Feith's War and Decision: Inside the Pentagon at the Dawn of the War on Terrorism is, in a word, fascinating.
Always swamped with a backlog of books, I picked this up one evening and found myself engrossed. As the former head of the Pentagon's policy organization, Feith can put you in the room because he was in the room. Whether or not you agree with the invasion of Iraq, this is an account that needs to be considered, especially since the press seems devoted to providing comic book-level analysis.
Those of you who share my enthusiasm for studies on decision-making will find Feith's dispassionate accounts of the meetings, the machinations, and the evidence to be especially interesting.