I'm actually in the middle of The Dark Tower series right now. It's bizarre and difficult to categorize, but certainly not horror. It's a curious combination of neo-western meets epic fantasy. A very interesting and diverse cast of characters, impossible to predict endings... I definitely recommend it.
So funny that you mentioned staying away from King because of his affiliation with horror novels. I was in the same boat. I won't be reading any more of his work aside from the Dark Tower series, but it's good to know that he has some versatility.