I would think that at her age, the existentialists like Sartre or Camus would appeal. When I was 17, Sartre's play No Exit made a big impact on me. I, personally, never cared for Camus but if she's a Cure fan, she should readily appreciate The Stranger.
Then, of course, there are the Russians. I like both Dostoyevsky and Tolstoy (not so much Gogol); however, I find Tolstoy more readable. You could try something short like The Death of Ivan Illyich, which I really enjoyed when I was in high school.
If you can convince her to try authors that aren't so dour, I'd definitely second Jane Austen. Pride and Prejudice features a strong female protagonist, has romance which she probably would enjoy but never admit to, and has dialogue that should be savored for its wit.
I'd recommend Vonnegut, although I don't have as harsh an opinion of Slaughterhouse Five as the previous poster; however, I'd highly recommend Mother Night - a highly depressing book.
If you can get her to read SF at all, try to get her to read Doomsday Book by Connie Willis - that one will leave her feeling like she's been kicked in the head by the end
And, my favorite book which is overall uplifting but has elements of tragedy and fear: Watership Down by Richard Adams. Don't let the fact it's about bunnies deter you.
Oh, and to the person who brought up Thomas Covenant, while I enjoyed the first two chronicles, I'd say The Gap series by Donaldson had more of an effect on me. I'm not sure I'd recommend Donaldson to a 17 year old girl unless she were a particularly mature reader.
Michael