Kids Summer Camp. One or two weeks of programs. All sorts of ways to do it - either all day all ages, or younger kids a.m. and older kids p.m. Then hold races at the end of the two weeks with a big party for everyone, including parents, grandparents, siblings, etc.
May even add a couple of evenings of family classes for adults new to sailing.
You'll probably want to get certified from US Sailing as it makes it look better for your club, and you learn so much about safety and how to run the course. Teenagers can get certified as well. Hopefully there are a few teens or college age kids that want a summer job running such a camp.