Here some pics from a tour of the Haunted Mansion a few years back.
This is a pic from the ballroom floor looking up at the ghosts who hang from the chandelier. The glass next to them is the hallway where the doombuggies travel.
Another ballroom scene. Here we are against the back wall. It's tough to tell, but that's as far as the stairs go. The rest is painted on.
The famous organ. This is a replica of the Disneyland one. Coincidentally, the Disneyland organ is the organ from 20,000 Leagues Under the Sea movie.
The seance room (pre-refurb). You can't tell from here, but the table is completely surrounded by a 15 foot pit. Allegedly, some guest hopped out of their vehicle, fell down the pit, but wasn't rescued until the end of the day. Apparently, the screams for help were just thought of show audio.
The famous "Donald Chair."