I don't know if anyone else is into hard science fiction, but I might save someone a few wasted days here. I finally ran out of books by the astoundingly great Alastair Reynolds (one of my favorite authors of all time now), so I wanted more hard science fiction. A bunch of places online said Iain M. Banks 'Culture' series of novels are fantastic and genius and visionary.
Do not listen to those opinions. AVOID.
I read Consider Phlebas, the first novel, over the course of a few days. It was marvelous. Richly developed characters, exciting and unique story, just fantastic. Not quite as good as Reynolds, but a hoot. Until the last 10% of the book. I won't spoil, but it made the other 90% pointless. Dumbest, most pointless, most unfulfilling to a book I can remember. As an extra insult, I liked the first half of the book so much I bought Book 2 of the series before I finished. So now I am slogging through out of raw spite.
Anyway. I do highly recommend Alastair Reynold's superb books, most of all Chasm City, which is one of the best books I've read in 2-3 years.