It all comes down to who you're meeting. Person, character, gimmick, age, etc, should all be taken into consideration.
If I was lucky enough to meet guys like Taker, Bret Hart and Vince McMahon I'd probably call them "Sir." But the younger guys I'd just call them by their character names, Cena, Edge, Jericho, Christian, etc,.
All depends on the person and where you're meeting them.
BTW, this was a pretty good article about Lance Storm on WWE.com.
Lance Storm