For nostalgia sake, it is fun to read how Disneyland described the attraction back in the day. Iconic items like Madame Leota, the ballroom organist, and the hitchhiking ghosts get the appropriate mentions. But other characters, like the headless guardsman and the dueling portraits get equally prominent mentions.
The press release says the Haunted Mansion cost $7 million to build and took 10 years to develop. It says the attraction has a ride capacity of 2,616 per hour (assuming two people per doom buggy). In the real world, it is a good day if they can get more than 2,000 per hour with the frequent stops for guests with disabilities.
Also of note, the press release ends by stating the Disney company had a total capital investment of $150 million in the theme park. They never include these types of details in press releases nowadays, so it is interesting to see the ride capacity and financial information getting this much attention in the official press release.
Update: Daveland Blog has some great photos of the Haunted Mansion in its opening year.