I can’t tell you how many times I hear the presenter say, in a demo, "I've saved the best part for last..." And this is offered after (often) an hour or more of demo details and day-in-the-life feature-function-flow.
Who is left in the room at that point? Certainly not the high-ranking people.
And how are the remaining customer participants’ brains? Mush.
So don’t save the best for last; instead Do the Last Thing First! (What a great idea…)