Good ten day trip in Europe?

I think your idea is good. You can do Auschwitz as a day trip from Krakow. With just ten days you did good that you did not plan more than 3 cities. I think Amsterdam is a good choice. Very good train connection with Paris and many flights from there. Hopefully you would be able to fly direct to Krakow.

What airport will you be departing from in the US?
Depending on your dates and point of departure it might be more cost-effective for you to fly open jaw into Amsterdam from the East Coast, eventually returning from Krakow after your stop in Paris. As I recall KLM runs a non-stop from Krakow to Amsterdam (connecting there for your flight home) that might be a very convenient and cost-effective option for you.

Could take the train from Amsterdam to Paris, then a low-cost European carrier from Paris to Krakow. You could also do it in reverse : ie fly open jaw to Krakow, visit Paris, then return home from Amsterdam. Point being that it might be cheaper for you to avoid Paris as the terminus for one of your overseas legs. Worth checking anyway.

Robert, I would be flying from Charlotte, NC.

Should be able to get some competitive pricing from a United hub.

What airport are you flying home from? My only thought is that personally, after Auschwitz it's nice to spend a little time in another city after that before returning home (maybe the last day in Krakow?). It's just that I know Auschwitz is an intense experience and after dwelling on it for some amount of time, it's nice to spend a little time somewhere else to remember that the world is still an ok place before the long trip home.