My favourite part of any story is in the middle. The characters and situation are set up, the (usually) life versus death scenario is well under way, and it is a question of whether you can outguess the author as to the resolution.
I love it when I guess correctly but love it more when a writer wrongfoots me here. I then go back and re-read the story and inevitably find clues over the unexpected resolution that had been there. I just hadn't paid enough attention, which is an object lesson in itself!
Naturally, I can apply what I learn here to my own writing, but it is also no coincidence the stories I re-read are the ones that have kept me on my toes. There is just so much enjoyment to be had here.
The great thing with twist in the tail stories is the simpler the twist the better and more effective it is. Simple doesn't necessarily mean easy to guess at either, as it is easy to overlook or forget the "obvious".