Whenever we do demos without much floor space, we usually have one game piece and one goal. We'll also bring cones to set up an obstacle course so people can try maneuvering the robot around on the floor. We have a dongle that plugs into the competition port on the OI that will allow the channel to be changed, auto mode to be enabled/disabled and robot control enabled/disabled. We'll usually have a MOE member at the secondary controller station or right behind the drivers ready to switch the disable switch on the controller in case of an unsafe condition.
When the motors get hot, we'll open the access panels and let everyone crowd around and we give a tour of the inside of the robot. People really like to see motors, wires, and other electrical-type stuff inside a robot even if they don't fully understand what it is. It looks high-tech and exciting.
<edit>The dongles are usually pretty popular with teams, and they aren't difficult to make. For help making one, the best resource is CDID: The Lucas (Brian Lucas). He is a MOE Alum turn electrical mentor that helped make a bunch. I didn't ask him if I could use him as a resource, but it should be cool.

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