Move along, move along...
Next I'll find a way to lay down only those dungeon tiles the heroes can reasonably see! (very though since most quests require tracking mobs in separate parts of the map - but laying the whole dungeon out kills the sense of suspensful foreboding I'd love to experience as a player...)
I am using line of sight for this. I drop the next set of tiles on the map as soon as any hero with line of sight would be able to see them. So the layout gradually grows. It slows down the flow a little, but definitely adds to the tension…