Just crawling out of my ARCS hole and dusting myself off to list my recommended conditions for doing a textbook:
1. You really love the material you are working on. I mean, really, really love it, and you must feel it is important (politically, morally, whateverly) to make the material available for teachers and (even more) for students. Just wanting to make money is really not enough IMHO.
2. You are willing to work your ass off every five years for a new edition--that is if it goes into new editions.
3. You are surrounded by loving people--near and far--who will put up with your muddle-headedness and who will understand when you say nothing is new.
4. You don't mind being consumed for a very long stretch of time.
5. You can adhere to deadlines. These deadlines are quite serious.
6. You can find a good research assistant who will respond to your piles and pleas, even though the work can be a real bitch (search engines simply aren't equipped for the kind of hunts we do). Relatedly I have some public library observations to be made at a later date.
7. You have a coauthor who is smart and honest and supportive and whom you admire and respect a hell of a lot.
Luckily, I have all these things.
And I still can't wait to be done!
Okay, back in the hole.