I'm wondering: When you guys - tharris and Pancubuzz - say you are doing a rewrite, does that mean an edit that starts at the beginning and goes through the whole book, or do you mean you throw away your draft and start all over without referencing the earlier version or doing any copy/paste?
@WeaselFire: Go with the Maserati.
It depends on the story, to be honest, this is actually my third time doing a rewrite (not on the same book!) The first time I did it, I wanted to rewrite the 2nd and 3rd book in a trilogy that I hadn't touched in a couple years (I'd been reworking the first one for ages, but not the other 2). For those two, I opened a blank word document and rewrote everything but one scene from scratch. The plot, the character names, the powers; a lot of that stuff I kept the same and built on it, but I felt like my writing had improved too much to settle with adding and editing, and that to do the story justice I needed to do it without copy/pasting. With that story, I definitely think it was worth it.
The one I'm rewriting now, I am again opening a new word doc and I've written the first chapter from scratch since the premise itself is new. However, there are some explanations of the magical theory that I have copied and pasted into the new version, and I think there will be a few scenes concerning character development/bonding (especially later on in the second book) that I will simply be copying and pasting. I always keep my early drafts in case of needing a reference or side-by-side comparison. But a lot of the scenes to do with the plot and conflict will be written completely from scratch.
(And then I will have to do the cursed start to finish edit of course XD )