Look to Windward is a strong entry in the Culture series. It is delightful, emotional, intelligent, witty, and wildly inventive, with nice tie ins to past events and the far future. Plus it has sentient cats, in their little cat military uniforms and with their religious texts made out of string and their arch-catty reparte. Who is a cute wittle authoritarian society? You are! Yes you are!
How these books have not been made into movies, or how people mention Ken Mcleod and the rest in the same sentence as Banks, I have no idea. This is perhaps not the best Culture book, but it is still very entertaining and is far above most sci-fi in the pure intelligence and general quality that oozes from the text.