I think something like a 50's themed hunt could be fun. You could collect things like records and it could turn into something like a jukebox key or a box or something. I like the idea of 50's themed Avis.
We can have the summer hunt and you need to collect like drinks in can eg.coke or fanta and then collect popsicle sticks to create a pool and you have to open it with a key or a skimmer plug?