Gail Carriger, who wrote the Alexia Tarabotti novels (series completed), will be writing a four-book young adult series, The Finishing School.
The Alexia Tarabotti books were a mash-up of steampunk, supernatural (hot werewolves and vampires, not so hot ghosts), and Georgette Heyer's wittier historical romances. Also, if you've read the Amelia Peabody books, the main characters were sort of like Amelia and Emerson but, you know, supernatural. That is not a complaint, just an observation. Emerson is very werewolf-like, anyway.
The first Alexia book, Soulless, won a YALSA Award in 2010. I like these books, but I don't really see anything about Soulless that would "have special appeal to young adults, ages 12 through 18." Though we were probably still in Twilight frenzy back then, and Soulless did have plenty of vampires and werewolves.