Geological tour / zombie attack :)
Eastern Oregon has a lot of ghost towns and a lot of cool rock formations/fossil beds. This could be a day trip or an overnighter depending on where the tour starts. Participants get a bus tour of Eastern Oregon with geology lectures and rock hunting. somewhere along the way, near a ghost town the bus "breaks down" -maybe overheats- and participants have to leave the bus to get water -or whatever- to get back on the road, fighting zombies along the way (airsoft only). It may be possible to charge a small amount to be a zombie.
Reward: a free ride