"Edwards has said for years he isn't interested in the AG spot. He wants a Cabinet post..."

Attorney General IS a Cabinet post, and generally considered one of the three or four most desirable or "highest ranking" among all such appointments ~ if not the very first.

It has often been reserved for the President's closest personal ally, because when worse comes to worst, nothing is more important to the Prez and/or his policies than skilled legal representation at the very top of the Justice Department.

Bobby Kennedy as his older brother's AG is the most obvious example. I believe that several recent Presidents have installed their campaign managers as Attorney General.