With Lufthansa, usually it's "Sir", but sometimes "Mr...". I did get some dirty looks once when travelling Economy as a LH Senator when the cabin staff greeted me by name and offered me (and no-one else) a newspaper..
But I was once called "God" by a BA stewardess. It was during a stop over and we were at the same hotel. I distinctly remember her saying "Oh God, oh God, OH GOD!!".........
