Speaking of revisions and rewriting and editing and all that good stuff...
One other thing I work on as I revise my manuscripts is unity of voice. I want my books to read as if I wrote them in one sitting, to make the reading experience more enjoyable and less disruptive to the reader.
I know there are some writers who write basically only one draft. They "get it right" the first time. I can't, and one reason I can't is that my "voice" is too susceptible to the daily influences of what's going on in my life. If I'm having a bad day (bad news, PMS, it's been raining for the entire week), my writing, and the "voice" in which I'm writing, tends to reflect that. If I have a good day, that affects my writing and my voice, too. So one thing I aim to do when I revise is to make the voice consistent, so that the individual highs and lows aren't obvious.
This becomes easier to do with each subsequent draft, as I can work on more pages at a time. I can write between 10-15 pages a day for the first draft. I can revise many more pages/day, so the "mood shifts" in the prose become easier to spot and correct.
This isn't to say I don't change tone or mood during the course of a book. Sure I do, but if I've done my job right, those changes depend on what's happening in the story, not whether or not I'm having a bad day, or (I hope!) a good one.