My to-go favorite for relaxed summer evenings is "The Master and Margarita" by Bulgakov.
It is a literature masterpiece that magically adjusts to my current inner state. It can be both easy reading when I'm tired and just want to unwind, and thought provoking when I'm ready to be thoughtful.
https://www.goodreads.com/book/show/117833.The_Master_and_Ma...