Public vs. private schools

No, this is not a policy question.  Rather Jenny, a loyal MR reader, asks for advice:

As an economist, I was wondering if you could provide any insights to us parents evaluating public versus private elementary schools for our kids…By comparison [with the good private school], my public school education seems shoddy. But at $21,000 for kindergarten and a younger sister that would be joining him, this is a huge financial commitment, and takes away our flexibility to do anything but grind away for the next 15  years. My son is bright and curious – how do I know that he will get that much of an incremental improvement being in private school? And despite my very non-inspiring, and at times dreadful, public education, I can’t say that I’m any worse off for it today…I’ve been really struggling with how to evaluate this. Can economics shed any light?

I faced this same choice myself as a kid and I ended up telling my mother I was happy to remain in the public school.  If nothing else I feared the commuting costs and not having friends’ homes be nearby.  Furthermore at public school I met Randall Kroszner and Daniel Klein, among other notables.  Natasha and I faced this choice again with Yana and she ended up in public high school.  I can’t really cite economics here but if your public school is halfway decent that is the side I come down on.

Readers?