I have a series of six caches in Highland Park in Saint Paul called Plato's Five Gems. Four of them are puzzles, one is a two-stage multi that has a puzzle at the first stage (by the way, this post by Spinowner suggests to me that I am correct, or at least justified, in classifying this one as a multi and not a puzzle), and one is a traditional.
Some recent posts on the MnGCA forums have given me an idea about this series. First, Silent Bob suggests in this post that there should be an 18 month time limit on caches. Second, pfalstad suggests in this post that hard puzzles should not be taking up space in city parks in cache-dense areas.
Some folks have had trouble with these puzzles, so I guess they're hard in some sense, and Highland Park is indeed a city park, and this series takes up a good fraction of that entire park's cache-able area.
Here's my idea: the "container" for the cache that ties them all together, Plato's Five Gems: Bunganator's Grand Slam, is a large icosahedral die, and the finder signs one of the 20 faces to log it. (See this blog post by Sokratz for a discussion on whether this is a proper cache container.) At this moment, there are 10 finders, and so there are 10 faces left to sign. I propose that when there are 20 logs on the grand slam cache, I will archive the entire series.
The only thing that gives me pause is the expectation of cache permanence in the guidelines. And I don't want to archive the series simply because some people don't do or hate or ignore puzzles. But still, it might be fun to create a sort of race for the last 10 finders, and then the icosahedral die would be a keepsake (or potential travel bug?) containing the names of 20 puzzlers.