Compared to yesterday this one is easy. Last year at Animefest I got to play through a Pathfinder adventure with one of my kids. On the same side of the table! For the first time! Details are here.
Animefest 2014 is this weekend and we're hoping to do the same thing this year too.
Runner up: A local con in the late 80's where we fought Godzilla with Battlemechs. It was a bigtime miniature battle and it was a lot of fun. This was very early in the Battletech game's life so the miniatures were all of the plastic model-kit type mini's, not the metal ones everyone knows today.