zombie84 said:

But I should mention that Making of Revenge of the Sith by J.W. Rinzler summarizes and has some lengthy excerpts from all the Episode III drafts. It's also a pretty good book. Episode II's early scripts are pretty much a mystery.

Yeah, I have that book. (And there were SO MANY leaks about ROTS during production that I think I knew virtually every development along the way.)

But what about TPM in particular? That's the one I'd like most of all, since it seems to be the most different from the finished movie and also because I think an early draft of that, since it was on a largely blank canvas, could reveal completely alternate routes that the PT could've taken.