Call me crazy, but what if the Miers pick is about trying polish his legacy?
The Miers pick is just so off the wall that I can't make sense of it. Is it possible that Bush knows that Miers is pretty much a moderate and is willing to blow off the Right because he doesn't need them any more? Cheney will never run and if he is greedy enough to run, would not win. There is no one at the top of the org chart in the West Wing that is in a position to need the support of the Right for an election. Most of those people are going into lobbying after this gig.
Bush fancies himself a great man, and is concerned about his legacy. He is probably picking carpets for his Presidential library right now. Because of the top down nature of his Administration, no bad news was allowed to filter up and he got his ass involved in this war. I'm pretty sure that he realizes what happened and is now just trying to get through it, much like a drunk just tries to get through the day without drinking.
I think that he knows that history will not judge him well and he is trying to build up some credit in political heaven. The Miers pick, a solid moderate, will not turn the country upside down.