I'm a member of another "fan" site for a defunct park, and each year, they take a poll of several dates, to see when the most members can show up at the site, at the same time. They usually visit the former park, then all get together at a local eatery & share stories, pictures, souvenirs, etc.. We should do something like that, to have a "live" scavenger hunt, once a year, that would be fun!
I'm still excited about a once a month scavenger hunt, that way those that can't go that often, will still get a shot at the fun.