The chicks have been incubating now for 9 full days. The kids and I decided to pull the infertile eggs and those with chicks that have died. We found 9 that were infertile, and 3 that had died. I threw away most of them, but kept one that had a 3-4 day old embryo for an impromptu science class some time later this week.
Of the remaining eggs, the majority had very obvious live chicks inside, swimming around, doing somersaults, etc. We really can't tell if any of my wife's eggs are doing well or not; the shell is too dark. Seven of my sister's eggs have live chicks in them; we couldn't tell with her eighth.
We're half way through the process now. It's strange to think that in just two weeks, we'll have a flock of chicks that were just eggs two weeks ago.