I just read The Magic Circle by Katherine Neville. It's not a bad story but...
That final scene? A breathtaking fight that is made all the more suspenseful because they might go over the horrible, deadly, perilous waterfall!
(spoiler) They do.
And nothing bad happens to either of them.
Um, that was pretty lame.
Funny-- before I read this, I was already considering posting about one of her other novels,
The Eight, and for a similar reason. The characters spend the whole book tracking down the MacGuffin, and when they finally get hold of it, instead of anything interesting happening, they basically decide: "Yeah, let's go home and not do anything with this."
The odd thing was, I loved the story, and was considering reading more of her books until the ending fell flat. And from what you say, it sounds like a common problem for her.