I just switched back to hospital work from private duty, and its taken me a few weeks to get used to the 12 hour shifts, but I think I have.
The good point though about 12 hours, is that (at least at my hospital), 36 hours, or 3 shifts a week is considered full time, with benefits. I also have the added benefit of self scheduling, so if I dont want to work say, on tuesdays, I dont have to.
Not to mention, you'd have 4 days off a week with your child. Right now I continue to do Private Duty on the side, as I'm not one that can sit around and be off 4 days a week. But, I'm really looking forward to being able to work only 3 days a week when husband and I do decide to have a child.
Its really not that bad!! Good luck with it