I've never actually read any of King's novels but I'm curious what all the fuss is about which is why I was asking the question. I've heard good things about The Stand and The Shining as well as the Dark Tower series.
I have a love/hate relationship with Stephen King's writing, sometimes he releases some of the best plotting and character development I have ever read, other times it's the opposite. Stephen King has super-impressed me this year. My wife and I listened to the audiobook version of Under the Dome earlier this year, and I was blown away. It is not only the best Stephen King book I have ever read but it is probably the best book I have in the past decade, without exception.
As a side note, please do not judge the book by the TV show of the same name. The TV show is pretty good, but has nothing on the book.
I actually disagree completely with dgrwriting regarding Under the Dome, I thought it had the worst deus ex machina ending and that ruined everything that came before it for me. I'm really enjoying the show.
I love the Green Mile, I think it's his magnum opus, and I also really like Needful Things, it's a bit of a cheesy, guilty pleasure. His earlier short story collections are also very good.