To be honest, 11/22/63 sounds like the first Stephen King book I've been looking forward to be for quite a while.
Have you read Duma Key or Under the Dome? Two of his more recent books, both of which were excellent. Not quite in the same tier as "The Stand", but quite worthy reads for a King fan.
Not sure how I feel about the time travel/Kennedy thing......I'm sure I'll pre-order the hard back just like I do every other King novel and I'm quite sure I'll read it, but it's not piquing my interest like Under the Dome did when I first heard about the concept.