I nominate The Sparrow by Mary Doria Russell. From Amazon:
In 2019, humanity finally finds proof of extraterrestrial life when a listening post in Puerto Rico picks up exquisite singing from a planet which will come to be known as Rakhat. While United Nations diplomats endlessly debate a possible first contact mission, the Society of Jesus quietly organizes an eight-person scientific expedition of its own. What the Jesuits find is a world so beyond comprehension that it will lead them to question the meaning of being "human." When the lone survivor of the expedition, Emilio Sandoz, returns to Earth in 2059, he will try to explain what went wrong...
I also second The Hitchhiker's Guide to the Galaxy and City at World's End.