What would you do? Honestly I would focus more on the queue line. I mean either at the entrance of where the tombstones are I would have a few actors dress up as "Dead Singing Carolers" who would sing the Haunted Mansion Holiday Scarolls that you hear being played over the speakers. Plus I would only have the singers come out during december (or whenever most other Disneyland carolers come out to sing in the park).
What would you do to make the Haunted Mansion Holiday experience better?