This is one of the reasons I've left my career and now work part time at the weekends. Sure we have a lot less money, but I'm always there for my kids (3 and 7) and the wife loves her career so stuck with it where as I can't stand work. Summer holidays for me means getting eldest out on her bike with me everyday, youngest is in nursery 3 days a week so the other two days we will do fun stuff.
Wouldn't change it, I guess I'll have to go back to work full time once the youngest is in school. I don't know why more dads don't do the same, finances permitting, kids are only young once and there's nothing I like doing more than spending time with them, plus there is always someone there for school runs and holidays.