The problem with writing science fiction is the details. I've chosen an orbital as the setting for a story and as soon as I did that I hit problems. I've dodged one bullet by putting the main character in a curated section, its essentially a military sanitorium, so there's no great need to invent a novel biology to populate the place or become happy with how it was built.
I did wonder about night and day cycles, though. How would that be accomplished on suImage via Wikipediach a vast structure? There are a couple of ways. Larry Niven's ringworld uses "shadow squares" set close to the structure's star that block the sunlight at regular intervals. What is most interesting about doing it this way is that the sun is always directly overhead. To someone raised on a planet that would be deeply unsettling, I'd guess. It would really underscore their sense of dislocation.
There are other ways to do it. Iain Banks' conception of an orbital generates a night and day cycle by tilting the vast structure on its orbital axis. That'll also help give the structure seasons.
One other big difference to living on an orbital/ring world would be the lack of a horizon. Again, that would be odd for a planet dweller. Instead, the vast structure would divide the sky in day and night and its great curve would lead the eye off and away until it merged with the sky.
The final question I've got to come to terms with is how many such giant structures there are. The story demands that there be enough for there to be a question over which one the main character finds himself on. So, more than four and less than 30, I'd say.
The implication of having loads of them is that the societies inhabiting these galaxies are far more advanced than I'd like. What makes the setting interesting for me is its limitations. I don't want to write a nanotech = magic = anything is possible SF story. That's just fantasy in a vacuum suit. I'm not kidding myself that what I'm depicting is plausible or likely but I want it to be true to itself. If anything is possible then actions have no consequence. You're dead? Don't worry, we can fix it. I'm more interested in worlds and cultures that are striving, are looking for that next great leap forward and can stumble along the way.
This stems from my niggling doubt about the Minds depicted in the Culture books. For me, they are too smart. That over-arching intelligence can see a hundred thousand ways to solve a problem that puny human or alien brains could simply not come up with. So, why don't they solve all problems, for everyone? I'd also guess that any significantly smart entity would also be happy with expediency - ask them about greater good and they will give you actual numbers. They also be intimately acquainted with the danger of error. They could be very, very wrong. The ultimate encapsulation of that old saw - experts are not necessarily right more often, they are just wrong for more complicated reasons.