Originally Posted by PorkRind

Because I prefer to have options I can exercise right up until I'm safely ensconced in my seat, and it's just as courteous to give the upgrade to someone I may be inconveniencing by asking them to move. Moreso, in most instances. And there's always the positive feedback of gratitude shown by the freshly upgraded . . .

By slavishly following bocastephen's rules, I wouldn't even be able to give the upgrade to my traveling companion.