Bart,
I tend to agree with you regarding formality and addressing people. It is nicer to err on the side of caution in most cases. I come from a scientific background - where I was on a first name basis with my advisor UNLESS we were in a more formal setting - like a class, or an exam, or a presentation setting. Curiously enough, I've worked with quite a few PhDs who refuse to be called by the proper "Dr. So-and-so". People are interesting...