The only Stephen King book I ever finished was "The Tommyknockers". I've picked up a couple of others but put them down within a couple of chapters as I was completely ungripped.
I'm the same way with Tom Clancy. I've gotten partway through a couple of his books and been like, "you know what, I just really don't care what happens..."
Stephen King is hit or miss with me. My wife loves him though so we have all of his books. I'll pick one up from time to time. Sometimes I'll lose interest before finishing, but usually I'll finish. His writing style is familiar and it's interesting to read stories that are set in places I've lived/visited.
Some of his books I've really liked, others I didn't care for. I have found that I enjoy his dramatic works a lot more than his horror stories.
~Mike