Lollapalooza
Race directors can learn something from Lollapalooza, the well-known rock concert held this year in Chicago.
In addition to the well-known bands appearing on stage, concert organizers will hire the three amateur bands that win the online vote at its "Last Band Standing" page.
The process is amazingly logical. Ask your audience what it wants and give it to them. They now have a reason to buy tickets - to hear the bands they said they wanted to hear.
Race directors can survey event audiences - past participants, running club members, running magazine subscribers, running store patrons, etc. - ask what they want in a race, and then provide it. If you give people what they ask for, they'll be more likely to buy it.
It's just common sense - and smart marketing!