I have demonstrated Aikido a couple of times. Well, I think that it is best for you guys to just practice. I mean, you should just practice if front of the people, in the same way you usually train.
That way, people will get a good idea on your Aikido class.
After all, you may want to make people feel like they want to join your class right?
I think it is a good way.
good luck, and please tell us how it all ended.
(take it easy and with a smile)