What is the etiquette for addressing senior research staff and faculty members in an academic setting in the USA? A postdoc is no longer a student but at the same time he or she is (in general) not at the level of senior research engineers/scientists and professors. How should he or she address them ("FirstName" or "Dr. LastName") so that proper respect as well as confidence in one's "above-the-students" position is maintained?
Does it depend on the University, Lab group or the level of experience one has acquired before joining the present postdoc position?
Address senior research staff and faculty members in the same way that they do with you. You're "Robert Doe" and full profs are calling you "Bob"? Then you can do the same.
And if you are the senior, you are supposed to tell explicitly what is the tradition, in order to avoid embarrassment for juniors.