i just cant leave my freaking gps toy alone. what do you think of a "treasure" hunt on bikes through the woods using a gps? get teams of three and ride a loop to find the "treasures" come back and let the next team go. it could be done at any time during the week. just leave your time and on sat i could have some kind of awards for the ones most proficient in gps use.
sign up at my truck
come by and get the first packet(has coordinates and clue for location of first cache) and post the time you start.
find first cache and leave evidence that you were there. inside the first cache would also be the second packet required to find he second cache. the second cache would have the packet needed for the third and so on.
when you are done, come back by the truck and give time needed to find all of the caches.
teams could be spaced out every half hour so they dont run into each other.