I too have four children eleven and under, boy 11, girl 9, boy 8, and boy almost 1. So today that is a big family. But if I were younger and could get started earlier I would go for a large family by old-time standards. I don't mean huge like 10 or 12 buy big like say seven children. My grandparents had seven and were sorta poor and all seven were great successes. All the grandchildren grew up in smaller families and were much less successful and upwardly mobile.
What earmarks American children is being spoiled compared with children in places like Bolivia and Mongolia.
We're expecting our 8th child, 5th boy, in a few months. I think you've got a good point about children's being spoiled, or at least, being awfully comfortable compared to the majority of earlier generations or other societies. It's not so much the number of children in the family that makes the difference, but the fact that it's more likely that a child in a large family is going to have to work harder and make do with less ... partly because there's more work to be done with more people, and partly because there's less money per person.