I hear what you're saying, but most of what I've read and seen is very consistent. On one side you have the Dept of State, the CIA, some former Justice Dept (i.e. Jack Goldsmith), and most of the journalists and authors. On the other you have the neocons like Cheney, Rumsfeld, etc. The latter wanted a regime change and railroaded it through, pushing aside moderates and 'voices of reason'.
For what it's worth, Frontline does a pretty good job bringing in experts that were on the ground and in the meetings. It's not like State, the CIA and journalists or authors are saying different things happened.
There's a few people like Feith and Yoo are trying to justify their actions and contest the moderates/journalists/authors views, but they're the minority and they end up looking pretty stupid in the process.