The Awakening (Darkest Powers, Book 2) by Kelley Armstrong
I enjoyed the first book in this series, The Summoning (Darkest Powers, Book 1), and thought this sequel was a good follow-up. As with the first, it leaves the ending open for another book in the series.
This book picks up with Chloe being held in the facility she was taken to after running away from Lyle House. Simon and Derek are still on the run, Chloe is trying to deal with her aunt's duplicity as well as her abilities as a necromancer.
I think this series is excellent for YA readers. It's got strong characters and a good storyline, and most teen readers will love it.