My last time at Gencon in the back of the event hall there were many *big* maps for miniature/wargaming setups (Battletech and other systems).  There is very large and elaborate terrain and in some cases oversized miniatures.  I was hoping to give it a try, but how do i find those specific type of events in the catalog?

Historical miniature and Non-historical miniature events.  There are far fewer of these events than usual this year because many of the groups that put on these events aren't attending this year.

Battletech for example only has the learn to play events and the grinder which is an open battle.  These events are run by the rules publisher Catalyst Games.  Events in years past like campaigns or special games with oversized mechs and terrain were run by independent groups.