Book endings

I've recently read two of the 'hot' novels of our time; The Casual Vacancy by J.K.Rowling and Sweet Tooth by Ian McEwan (if you are now wondering where I find the time to read such huge novels; so am I). I loved both novels, but found problems with both endings.
With The Casual Vacancy (as with the Harry Potter novels), I was immediately immersed in the story (although I had to flip back and forth to remember who everyone was several times), and it kept me riveted towards the end. With Sweet Tooth, it took me a while to get into the story (it also took the story a while to get moving), but once I got into it, about halfway through the book, it swept me along. For both novels, this is partly because you expect them to end badly, and you can't help but want to know whether it does. The Casual Vacancy just contains so many destructive people, who hate both themselves and each other, and are willing to do anything to get their own ideas pushed through. For McEwan's novel, well, he's McEwan. Most of his novels end badly, or in some huge revelation you never saw coming.
Sadly, with both novels, the ending disappointed me.
I won't give anything away, but in The Casual Vacancy, the focus is on a large group of main characters and some secondary characters, and the ending of the novel consists of the musings of one of these side characters, which then throws another light on one of the main characters. It is nicely written, but not the climax you are looking for. It just shows that you as reader were right all along; that main character was more likable than any other character in the novel realised. But no other character (apart from said side character) realises this, so there is no real growth or process or catharsis, and you end up on a low instead of a high.
In Sweet Tooth, as I was reading the ending, I got the feeling that this novel would turn out to be some Inception-like loop, which would give a whole new perspective on the novel, and novel writing, and make you wonder if what you'd read was actually real, or a story, or a story about something real, or something that never happened and actually could not exist. But then, in the final two pages, this was blown away by some simple references, and it turned out that McEwan had pulled the same trick as he did in Atonement (but slightly different, of course).
This made me sad. It made me sad because it means that he really will never write something as good as Atonement and Saturday ever again (Solar was the absolute low point, followed by Sweet Tooth) and it made me sad that he (and his editor) did not see this metaphysical loop-like possibility of finishing. He wanted to write an account of the 70s, his experience of the 70s, and that is what he did, so he could not pull it out into something that might or might not be real.
His writing is still great, I love his style and the way his words flow and the way he describes a scene and a character and the small details that make everything real, and he will remain my favourite author for quite some time to come, I think, but still, it is sad to see someone past his high point. But everything has to end some time.