In Oscar Wilde's Canterville Ghost, the Otis family, generally speaking, strikes me as anything but crazy. As I see it, the purpose of the Otis family is meant to create a contrast between American rationalism and the more whimsical imaginations of the British.
Mr. Otis, despite being warned about the ghost, buys Canterville Chase anyway. When the ghost clanks its chains, Mr. Otis offers a practical solution: oil the chains.
Later in the story, after Virginia vanishes, Mr. Otis pursues a logical course of action in trying to discover his daughter's whereabouts. Later, after Virginia returns from her experience with the ghost, Mr. Otis gives his approval to her marriage to the Duke of Cheshire.
Given these actions, I'm not convinced that Wilde's short story gives much indication that Mr. Otis is "crazy."