I loved Bag of Bones, it's definitely in my top 5 (assuming I can lump the Dark Tower in as 1). It definitely had a different feel, but to me, it totally worked. Under the Dome is one of my favourites, I hope you give it another shot!
Bag of Bones is one of Mr. King's most literary works (however you choose to define the term). It's a gothic tale--old house, family secrets, ghosts, revenge--but it also touches on a larger, almost Lovecraftian, mythos. It isn't a fast-paced story with a flamboyant monster like Christine or IT; it's a subtle, more introspective take on the classic ghost story, with a tone often reminiscent of The Reach.
It's hard for me to say if it was one of his bests but it was good. The love story between Noonan and Mattie Devore wasn't really over the top and didn't give it too much of a "Sparks" feel in my opinion.
The story of Sara Tidwell almost had me thinking I was reading something set in the New Orleans area for some reason.
Brosnan as Michael Noonan seems an odd choice but everyone envisions their own characters when they read. Will make it a point to see the film.