I always recommend Ender's Game, even if you don't like sci fi, because it's just plain awesome.
Sounds like you might find "This Present Darkness" by Frank Peretti interesting. He's a Christian author but the book isn't an "evangelize" goody-goody book, it's an intrigue story.
I like Dick Francis mysteries quite a bit. Hot Money is a good one.
If you like Crichton, you should read Jurassic Park. It's a good novel. Timeline was interesting but not half so well done, I thought.