If I was organizing a demo, I would make it interesting to a casual observer.
For example I would create some kind of pseudo-soap-opera with some guy being mugged, like a mini-piece of a Seagal film.
Then I'd make sure that the guy can go total Seagal on his ukes and that those particular ukes can take it.
Let the fun begin !
A demo should be flashy. It's NOT A CLASS.
You're not EDUCATING anyone.
I have a videoclip of some Polish Aikido demo where they start with katate-tori tenkan and repeat it 4 times.
What a way to attract attention !
What's next, an Aikido demo starting with breathing exercises ?