I've always been partial to No Exit, I can't imagine being stuck in the afterlife with the same people lol. Another good one is The Chips Are Down, it's more in line with determinism rather than his usual existentialist tome. And lastly, The Devil and the Good Lord, this one is a hidden gem. Not many people paid attention to it since World War II was still fresh in their minds.
I just finished reading the first 5 Game of Thrones books, The Map of Time by Felix Palma. Its a historical fiction where HG Wells tries to save literary classics like Dracula from being erased from existence from a time traveller. It's a NY Times best seller so I grabbed it and I have a soft spot for historical fiction. I picked Conqueror by Conn Iggulden yesterday. It's the story of Kublai Khan and how he saved the Mongols after Genghis Khan's death.
Have you read Jailbird by Vonnegut, it was the only one they had at the store and since I wasn't familiar with it, I didn't buy it.