Just a heads up, The Dark Tower Series is in talks for a Trilogy.
1-3 are great.
4, you have to read a few times to really appreciate it.
5-6 are utter trash.
7 is outright disappointing, as SK has no idea how to end a story.
I'm extremely excited for this, although I agree with you on your last point.
The few endings that Stephen King has nailed have been crash and bash, Grand Guignol, as in The Shining, Bag of Bones and Pet Sematary.
I wish he and Peter Straub would write together again. I know they can put together something better than Black House.