how to choose a first job

How can you tell if a hospital is good to their new nurses? I've been on several interviews but HR and the nurse managers always seem so nice and supportive.

I would love to talk to the staff during the shift but how do I go about doing that? Do I excuse myself from the Nurse Manager and speak to them separately? How do I get an honest opinion about a particular unit?

I've seen so many posts here about having a horrible first experience and I don't want that to happen to me!