Sherlock Holmes stories are a perfect example of why I don't like reading mysteries. They're a one-time read for the most part. It's really hard to get more out of a story on a second read-through when pretty much everything about the book is building up to the big reveal.
Arthur Conan Doyle was actually pretty good about that - Holmes and Watson are interesting enough characters on their own that you don't really have to give a shit about the background mystery in order to enjoy the interaction between the two characters.
The Hound of the Baskervilles will never not entertain me. John and Sherlock are wonderful foils for one another. Watson is adorably solid and practical in the face of demon dogs and does a good job of being a friend and defender to Henry Baskerville as well as a spy for Holmes. Sherlock himself is more beautiful, funny, and impressive in Baskervilles than he is in almost any other story. The best view I've ever had of him is as the man on the Tor, hiding out in a primitive hut but keeping a smooth chin and a clean collar in spite of it.
Doyle, Arthur Conan. "The Hound of the Baskervilles." Sherlock Holmes: The Complete
Novels And Stories, Volume II. Bantam Classics, a division of Random House. New
York: New York. 2003. (Originally Published 1902).