I highly recommend anything by Michael Crichton and Michael Connelly. I enjoyed a lot of Robin Cook's stuff, but after about 15 of his books, they started feeling really similar. I have read about 60 of the Star Wars books, and have enjoyed most of them. If you don't mind REALLY long books, check out Ken Follett. I started Dostoevsky's 5 great novels, but so far, I have only finished Crime and Punishment. I have read a bunch of Stephen King and Dean Koontz, and both are OK. Maybe horror books just aren't for me. Seems like neither one really has mastered ending their stories. I really enjoyed Atlas Shrugged, Anthem, and The Fountainhead, by Ayn Rynd.
I look for authors that have a lot of books, and if I like them, I will read all of their stuff in order. Love this thread, as I am always looking for new reading material.
And if you have a strong disposition, try reading The Gulag Archipelago. A lot of it is difficult to read, but completely exposes socialism for the brutality of the ideology. If you are going through a difficult time in your life, it puts things into perspective to see the horrors that others have had to live through. It really made me realize how small most of my problems are.