I've often talked to people who say they don't like Stephen King books, and when I ask them what they've read, it's often a "different" Stephen King book that isn't really representative of his entire body of work (at least, to me).
The purpose of this thread is not necessarily to criticize these books--I love these books, and some of these may be the perfect first book for some new readers, depending on what you know about their tastes. What you recommend as a first book to someone really depends on that person's personality. If they tell me they don't like horror, I'm not going to suggest they read "It", for example.
But lacking any other reader-specific information, here's my list of books that I recommend you should NOT read as your first King book.
The Dark Tower books
The Eyes of the Dragon
The Talisman (and Black House)
I'd like to hear what people think of these choices, and feel free to add any books you think aren't good first SK books to read.