Heres in idea for ya, Ive been wanting to make it my self but im still trying to finish a few of my other ones and fix/edit some of the ones I already have out....
A siege map where the attackers start in a dungeon (a simple one, since the masses respond better to simple) and then the make their way out to a courtyard and into the keep. The whole map is the castle though u can see the outside i would barrier it off myself so no one goes out there. I think it would be an interesting twist with its own unique challenges for the players and map maker.