You could always play with timing...for example, if you are using your bright lights to sort of blind the patrons so they can't see what's coming, you could try total dark, quick flash of light or sound to distract in one direction, followed by a very quick scare from the other side. And I've also found that having multiple small scares in an area allows you to "skip" a scare here and there and hit them with another. So one group might get hit by an actor jumping from above near the exit of a room, another group might get hit by a drop panel at the beginning, and other groups may get both.
All in all, I always feel that the expectation of a scare can be extremely unsettling...resulting in the perfect setup for the next scare. So having flexible options allows the scare to move and still keep people a little off balance.