My club's demo/s are more of an open house. It's open to the general public and of course family and friends, and is more of a big party that invites people to try out various things as well as talk to the students and teachers. The last one had people trying out sharp sword cutting against tatami mats and shooting airsoft pistols. And yes, one or two students have joined because of that.
However, the most successful recruiting tool has been a joint program between AEMMA and the Royal Ontario Museum. For six weeks, every Saturday, a group of twenty or so folks of various ages can train in the fundamentals of using an arming sword. This was first done in the ROM's Grand Gallery, and later transferred to our home location because of the museum's renovations. After six weeks, the ROM class can train free for a month, and some of them stay on, train hard, and get really good. Thus far, all the feedback I've heard has been extremely positive.