Focus on Mystery and Adventure:
* The Thorned Secrets of Sleeping Beauty
* The Skeleton Key to the Sleeping Castle
* The Prince, the Thorns, and the Whispering Bones
* The Mystery of the Thorned Guard
* The Bone-Chilling Tale of Sleeping Beauty
Focus on Humor and Playfulness:
* The Prince Who Couldn't Sleep (Because of Skeletons!)
* The Skeletons in Sleeping Beauty's Closet
* The Thorned Tangle and the Bony Surprise
* Prince Charming and the Bone-A-Fide Mess
* The Skeletons Who Just Wanted to Dance
Focus on the "Why":
* Why Are There Skeletons in Sleeping Beauty's Garden?
* The Secret of the Thorny Guard
* The Skeleton's Story
Bonus:
* The title could also include the Prince's name for a more personal feel.
Ultimately, the best title will depend on the tone and focus of your story! Good luck with your book!