Can I talk about The Man Who Folded Himself for a minute?
Best Time Travel Novel, EVER. It has a lot in common with All You Zombies, but it takes a self-consistant model of time travel, and really pushes it to the limits of "what-if". Now I usually hate time travel, because most stories don't pick a consistent model. One time you go back in time and change the past, the next time you go back in time but set up the future you were already from. But this book sets up the rules, and then plays within them. And it gets crazy, with the party house in the pre-historic past populated with hundreds of variant copies of the same man from different timelines living it up with themselves. There are just some great ideas in here. This is a book that takes one classic SF trope, and really sees what it can do.