I don't think I could have done anything much differently for SO. I can only think of two things
was not starting meta.stackoverflow.com sooner, but that still came relatively soon.
splitting into two projects, careers and stack overflow proper, so early on with so few people working
#2 was painful, and I can technically blame Joel for that, but we felt it was key to get the income part of the project going as soon as possible so we could figure out how to make it a sustainable business.
I think the Q&A format was less relevant to programmers back in 2007.. though it was in fact was ASTOUNDINGLY common on the web! It blew my mind how many random Q&A sites there were on the web when I began researching it in 2008! People may laugh (and justifiably so) at Yahoo Answers but it had crazy levels of real world usage by real people. Q&A was a latent market, I think, and we tapped into that for the programming use case.
As far as work/life balance, I think integrating more women into the field will help. It's awfully easy to work 12 hours a day when you don't have any children in the picture, and this goes for fathers as well as mothers.