I've really enjoyed both the TV show and books for "the Expanse" series. A big part is the sophisticated, mid-future (~200 years) world building. Class relationships are more developed than in most sci-fi stories (excepting 'the Dispossessed'), and makes me wonder if it's a good framework for exploring/illustrating socialist ideas.

The big class issues are depicted among the interplanetary diaspora, but there's also interesting dynamics within Earth society.

• Mars: A highly regimented society whose dominant ideology is focused on building a self-sufficient new world that leaves behind the decadence of Earth.
• Belters/Outer planets: Populated by an oppressed working class (dominated by Earth and Mars) with anarchist tendencies. Much of the economy is built around mining and hauling, often organized by corporations, but sometimes independent single-ship operations that function like little communes. The main characters are belters.
• Earth: About 1/3 of the 30 billion inhabitants survive on a social welfare scheme called 'basic' that seems to provide necessities but no cash. The economy is still fundamentally capitalist, with immensely powerful industrialists and a massive UN bureaucracy running the world. Ambitious people can take entry level jobs, which in addition to wages, provide credits that will gain them entry into free higher education, and access to more influential positions.

The Belters get a lot of attention in the series, but the 'basic' folk on earth are largely overlooked and presented as an underclass that the characters often struggle to rise above (to the point that they will even migrate off Earth). The book leaves the impression that the people on basic are idle and caught up in their petty squabbles, vices, and criminality. However, I think it could be possible to describe a rich, and even influential culture arising from the 'basic' masses. One obvious candidate would be religious movements. You could also have a vibrant arts scene, where there's freedom to develop skills without needing to serve the market. Philosophy and math could thrive. Even science and tech could thrive, to the extent that expensive equipment is not required. Anyway, I'm thinking of interesting stories to write within this environment. The belters obviously offer better options for drama and adventure, but I think there's something potentially interesting in basic too.