Generally the ideal is co-op; that's what my parents did. I know it's somewhat a radical idea, but you can make friends with other parents. Even with two or three families your individual responsibilities become much more manageable. Each parent can take off early once a week and 7-8 children come over to hang out. You do it right and they won't even really need supervision.

And since you've fostered relationships with the parents of your friends' children (or fostered your childrens' relationships with your friends' children) odds are there will be enough overlap in after-school activities that rides home are equally simplified.

Of course, this sort of stuff does take planning and relationship building, but generally it will be a lot less trouble than having a single-income household.