I also prefer the Quaker way. The Ascot racecourse mailing list has an amazing range of options to choose from: "Air Marshall" ,"Archbishop" "Countess" etc.
I always thought the US was more formal: "Senator Bloggs", "Congressman Smith", "Officer Krupke", but that just may be my reading of detective fiction. The South seems more formal but also less sincere ("sir" can be as offensive as "boy" in the wrong tone).
It also amuses me that those who got an honorary Doctorate or one by mail order or from a dodgy Bible College (yes, you, Paisley, Graham etc) are more likely to use it than those who actually wrote a properly argued thesis: for instance politicians, like Vince Cable or St John Stevas.

RtS