I think you should give the Fear Street series because trust me, they were made for people our age (definetly not for younger readers).
I would definently second Agatha Christie especially And Then There Were None. She always has suprise twists at the end.
One of my favorite books ever is The House Next Door by Richie Tankersley Cusick. Great ghost story full of suspense and romance (huge plot twist)
A Great series about witches (not really Wicca like the Sweep series) is the L.O.S.T series. Also Sign of the Crescent by the same author. Very romantic but not too suspenseful.
Gemma Doyle Series
and I guess I would try Stephen King, just to see if you like it (he is the king of Suspense as my friend would say)
"There would be little reason to lie down at night without the possibility of seeing things bigger and more amazing than the average day might bring about. Why pick up a pen or type on a keyboard if there's no imagination or wonder left to behold?"
-pg 3 of Leven Thumps and the Wrath of Ezra
