Well, it's Stephenie Meyer, but if you aren't huge on Twilight, you might want to check out the Host. It's completely different, and I liked it better than Twilight. Not as teenie/predictable (though I am a huge Twilight fan and enjoy most teen books, though most of them are somewhat easy to predict).
Other than that, here are some of my favorites:
-1984, George Orwell (The scariest book ever. Dark, and can relate to anything now)
-To Kill a Mockingbird, Harper Lee (Ahh, summer reading. gotta re-read soon)
-A Separate Peace, John Knowles (It's a tad dry, but I liked it)
-Daddy's Little Girl, Mary Higgens Clark (Mystery, and it's awesome)
-The Da Vinci Code, Dan Brown (It's pure fiction, so don't take it as fact, but it does make you think)
-A Corner of the Universe, Ann M. Martin (Such a great book, everyone should read)
-Interview with the Vampire, Anne Rice (Just makes you wonder)
-The Rifle, Gary Paulsen (Short, and it makes you think about guns, risk vs. reward, etc. Really interesting, though the beginning is dry).
Obviously, I really like books that make you think, and with strong theming, whether I agree with it or not. Next on my to-read list (behind re-reading To Kill a Mockingbird) is Wicked. My dad read it, and apparently there is a lot of theming about whether or not evil truely exists. Collections of Poe stories are also good, and Shirley Jackson's The Lottery is a collection of short stories featuring the Lottery, which is just very, very dark, and also heavily themed.
Another push on the Host before I finish up is that it also has Utopian themes, with a lot of thrill but relatability, and a feeling that it could happen in a way, and a fear of it happening, as well as more theming that I won't give away.
Happy Reading!