I suggest ditch the idea of having all the different movie monsters and pick just one as the end scrare guy or ditch them all together and make up your own.
Come up with some story that ties the area inside your haunt together, maybe about how the guy who lived in the house admired movie monster X and was recetnly caught killing kids, and the bodies were found in the basement.
Of course tell them that it is ok they cops caught him and there is no way he could escape, and that they are lucky today they are teh first ones to look into that guys mind and see what he was doing to those kids.
Then of course he had escaped, maybe have a half dead cop in there saying something like "He escaped, you must get out of here."
Try to break the cliche of movie monster jumping out of the dark saying boo.
while that will scare some people, they will not remeber the haunt as much as if it has a unique story and you terrorize them by using their mind instead of just jumping otu saying boo.