I decided to read the books in publication order. Doing so is not in any way necessary, since none of them are conventional sequels to the others. In particular, getting into the first book, Consider Phlebas, can be hard, so you might want to start with The Player of Games or with one of the newer books (Matter even has a handy glossary!).
Still, I enjoyed seeing how Banks developed his ideas about the Culture over time. If these books sound like your type of thing and you're ready to commit, I say publication order is the way to go.
Consider Phlebas (1987)
The Culture arrives! Actually, Banks had the idea much earlier, but this was the first book published not long after Banks's success with his intense non-SF book, The Wasp Factory, in 1984 (Banks also had a flourishing non-science fiction career). Consider Phlebas took some getting used to. The main character is a murderer, and, even worse, not a particularly likable one. The plot isn't always easy to follow. But the awesomeness that is the Culture itself, the humor of the AIs, and Banks's writing style all make it an amazing book. I realized I loved the Culture when I kept thinking about this long after I read it. See my Goodreads review.
The Player of Games (1988)
If Consider Phlebas is too daunting (and I totally understand if it is), this would be the best place for those new to the Culture to start. It's in the running for my overall favorite Culture book. Gurgeh is a Culture citizen, but a somewhat disaffected one who goes on a mission to a very non-Culture sort of place. And he plays games, but amazing, complex, dangerous games. The major theme of the Culture's relation to the rest of the galaxy is central here. See my Goodreads review. (See this post from the blog, Thank the Maker, for a discussion of the first two books).
Use of Weapons (1990)
Many people count this as their favorite Culture book (Do I? See the rankings below!). This has the style and subtle humor of the Culture novels, but what stands out is the unconventional structure. Alternating chapters move forward (in a relatively coherent story line) and backwards (in a series of flashbacks, or flashforwards depending on how you look at them). The backwards chapters make this a quite introspective novel, which is also the case with some of the later installments (especially Look to Windward). I'd also say that this is one of the most beautifully written. See my Goodreads review.
This is a collection of short stories, only a few of which are set in the Culture universe (a few aren't even science fiction). It also contains Banks's worthwhile essay, "A Few Notes on the Culture," which can also be found online. The title story features Diziet Sma from Use of Weapons who visits Earth in 1977. Hilarity and deep thoughts ensue. This is the only time Earth is even mentioned, much less visited, in any of the books. Remember: the Culture is not an extrapolation of our future; it's out there, going on without us. Are we Earthlings too barbaric for the Culture? (Spoiler alert: yes). Beginners not wanting to commit to a longer book could easily start here. See my short Goodreads review.
Excession brings us to what I'd call the middle period of the Culture books. The plot is complex. It focuses on the AI ship Minds and their efforts to understand an unusual phenomenon known as an excession. All of this can be hard for meat minds to follow. On the up side, it gives Banks a chance to create dozens of those amusing Culture ship names. Some examples: Frank Exchange of Views, Serious Callers Only, I Blame My Mother, Unacceptable Behaviour, The Anticipation of a New Lover's Arrival, and What is the Answer and Why? The main, non-AI character has a poignant and engaging story. This one's probably not for beginners. See my Goodreads review.
This is what happened when Banks wanted to write "a Culture novel that wasn't." You could easily enjoy this as a standard fantasy novel, but a little Culture background adds some depth and a fun twist at the end (you may have to squint, but there are Culture connections). There are two alternating narratives on opposite sides of a relatively low technology, fantasy type world. The stories and stories-within-stories are engaging and at times almost like fairy tales. Along the way, Banks gives plenty to think about concerning truth, narrative, ethics, violence, and gender. See my Goodreads review.
Look to Windward (2000)
One of my favorites of the series. It's a loose sequel to Consider Phlebas, although it would make perfect sense on its own for beginners. Unusually, all of the main characters are non-humanoid (even though the Culture isn't our future, it still somehow contains varieties of humanoids, who are the usual protagonists). The story of Quilan, a furry, five limbed Chelgran, is particularly good. I also love the Mind that runs the Orbital (sort of like a giant space station), which is itself a war veteran. You'll find thoughts on death, war, love, and regret and a rather touching explanation for why the Minds keep carbon-based lifeforms around, contrary to the fear of AI that I discussed in my review of the recent film, Ex Machina. See my Goodreads review.
Matter begins what I'd call the late period books. It was also the first book I reviewed on this blog, so I won't replicate that here. Beginners: this one has a helpful glossary and would make a fine entry point into the series, especially if you're interested in the later books. My Orbit edition also looks cool. See my blog review.
Surface Detail (2010)
Perhaps my favorite of the later books. This probably isn't an entry level Culture book. The stuff on digital hell realms is super cool as is the story of a "reincarnated" murder victim seeking revenge on her murderer. See my blog review.
The Hydrogen Sonata (2012)
my blog review.
Rankings: Early, Middle, and Late
I love each Culture book in its own way, but if I had to rank them, I'd do so by first splitting them into three periods: early, middle, and late (much like Plato's dialogues!). Some of these rankings may be controversial, especially ranking The Player of Games ahead of Use of Weapons, which many consider to be the best Culture book overall (I just like the story better). Nonetheless, I should reiterate that every book on this list is still probably better than most science fiction out there, at least if you ask me (and you are, since you're reading my blog!).
1. The Player of Games
2. Use of Weapons
3. Consider Phlebas
4. The State of the Art
1. Look to Windward
1. Surface Detail
3. The Hydrogen Sonata
As sad as it is that I'm now done reading the whole series, this means that I get to read them again to get even more out of these amazing books. Stay tuned for another post on my reflections on the series.
[EDIT: Click here for my overall reflections on the Culture series.]