It takes about an hour to drive there, as I recall, and they are very close to each other. Hire a private driver from your hotel for the trip. One day is sufficient. If you start out from Krakow at 0800, you should be back at 1400. That was my experience. I definitely think you should go as you are there and the site's importance in recent history. I must admit, I think the experience at the Holocaust museum in Washington, DC is a more moving experience.

GRF