Power
If you're conducting a tour, the closest you get to power is talking about long-dead people who once had it. You'll point out where Washington spoke or where Kennedy was shot or where Marilyn Monroe once ate a sandwich. You'll wield interesting stories about them, but you're not exactly following in their footsteps in the power department.

Well okay, so maybe you're literally following in their footsteps, but we mean you're not going to become president or a Hollywood star by relaying historical tidbits to children all day.
As far as the tour itself goes, it's not exactly the kind of place where you'll be exerting a whole lot of energy to keep people in line—not even when they're actually standing in one. Most people on a tour generally want to be there, and want to listen to all the interesting anecdotes you've said a hundred times (while acting as though it's the first time you've said them).
The exception, of course, are kids, but typically you'll leave all the disciplining responsibilities to their chaperones.