As I said before, I'm a little bankrupt for ideas on this one. It's an issue I've given a fair amount of thought in the past, but it's genuinely tricky. The new scene would need to be subdued, creepy, at least slightly logically sensible in terms of house layout, and not overtly haunted. That's tough. I think the whole idea of making it similar to DLP's loading area on some level is quite common; I know Disney has toyed with it, along with half of all the armchair Imagineers out there. Only having seen it in photos, I can't say how much I support the idea, but it does feel rather...Phantom Manorish, of all things. Not sure it fits with the HM tone. Now, the architecture and style and everything would of course be significantly altered to look similar to what we see in our Haunted Mansion, and perhaps that change would be enough. But the grandiosity itself might just be not quite right. I'd hate for the ballroom to lose some of its impact because there was already another scene of similar size.