We had a linkshell "anniversary" event about a month ago for one of the shells I am in, but the events weren't announced with enough lead-time to be able to put in a formal app to SE (stating locations using their special < pos > tool, type of decoration/text for each interactive item, etc.) so sadly we had to "wing it" without all the fancy items.
But if you were looking for ideas, this was brought up in another forum topic previously...
http://www.ffxiah.com/forum/?topic_id=4240#169420...some of the ones I suggested (or rather variations, like a lap around Ulegarand from entrance up to the top and back again, and the "find the moogle"--in this case a taru) were part of the events, even if we couldn't get the Player Event Support app in on time.