Player of Games by Iain M. Banks: A member of a post-scarcity society travels to a socially-primitive interstellar empire to play a very important game. Good mix of action, character, and social commentary
Children of Time by @aptshadow: Explores the history and culture of a non-human society while examining the nature of empathy and what truly makes us "human"
@grmpyprogrammer There are a bunch of independent books in #TheCulture universe, all of which are quite good IMO. After Player of Games, you might consider:
Consider Phlebas: An enemy of the Culture tries to find a Mind hiding on a dead planet
Surface Detail: A Culture agent and a victim of a powerful business magnate fight a cold war against forces that run virtual reality hells to punish criminals