Using dr.

I had a discussion at work about titles.  A friend just graduated with her PhD, and made a big point that this was the only time she was going to let us call her Dr.   And that brought up a much larger discussion-when do you use the title?
I generally find it to be "a PhD bomb" at work.  Sometimes that's a good thing-I can't count the number of difficult people that I've had to make understand that yes, I do know what I'm talking about, and yes, you do have to listen.  And other times I just want to say, "no, I'm not secretly judging you.  I don't think I'm smarter than you about your job.  I do want to hear what you have to say."   But I'm interested in hearing other perspectives.