When there's a space of time where there's nothing really going on (at least nothing I'm interested in), I'll take a breather in my hotel room and have a snack/watch some TV. At a convention I go to (Anime Crossroads), there's a courtyard where you can find people playing stuff like "extreme duck duck goose," which is fun, so maybe if there's an area like that, see what people are up to.
ACen 2014 cosplay: Lara Croft, Erio Touwa, Shirahoshi Hime
ALA 2015 cosplay: Shirahoshi Hime, Akemi Homura [Haregi ver.], Menma