She is working successfully in Germany with Geo-Caching events, have a look at her WS- she is also doing this in cities- I talked to her and I think this is very interesting and we might be able to apply a lot of her stuff in BCN. She specializes in children-birthdays up til now. But she is currently investing in an app- which is due for summer where people can easily create their own geo-caching tours- so this is really something to explore…
Unfortunately only in German, but there is a tutorial and maybe we find similar stuff in English, too
A colleague&friend has written this article- but that´s only sideinformation as it is in German