Grown ups want to be treated like grown ups. Ensuring that people are quiet when they should be, or getting them to line up in a specific format is just a matter of instruction. But the delivery of the command is just as important as receiving their cooperation. As with most directives, conveying a request creatively, politely, and with elegance garners greater enthusiasm and compliance. After all, events are supposed to be enjoyable for everyone, even those that need a little refresher on manners.
-MS