I have worked in higher education for over a decade now and always use Dr. or Professor until I am instructed otherwise. My best friend is a Ph.D and loathes being called Doctor. He insists that everyone refer to him by his first name.
During my undergrad years my favorite professor insisted that we call her Miranda instead of Dr. Joseph. I never quite got used to it. Perhaps because I had a huge crush on her coupled with enormous respect. It felt way too intimate.
I just started graduate school and noticed right away that no one raises their hands, they just start talking. I was so nervous my first day I don't recall how the prof. asked us to address her. I will pay attention today for sure!
A rule of thumb I go by is when introducing someone who has earned their doctoral degree to a stranger, I always use Dr. or Professor. My boss doesn't like to be called Dr. Katz but I still introduce him as such and leave it up to him to informalize the salutation.
With TA's I use Mr./Mrs./Ms.
When people accidentally call me Dr. L______, I never correct them.
