I was thinking, as I fell asleep, about my idea of one type of utopia, and decided that it's insufficient, so I began revising it in my head. Here's my new idea:
Extended families would live together in a pseudo-clan system, as in my previous system, but rather than being geographically isolated, a number of these pseudo clans live in industrialized cities, within a sort of gated community. The presence of cities allows for specialization and division of labour, which lead to the high standard of living we experience today. The pseudo-clans are responsible for their own property, so their communities are constructed and maintained by themselves, and their offices and infrastructure is as well. In these cities, due to necessity and because it's simply more efficient, many of these pseudo-clans work closely together to construct further public infrastructure such as roads and public facilities. Doing so is beneficial to everyone, especially those who construct the infrastructure.
In terms of commerce, I think it's likely that there'd be a sort of 'family business' system that functions similar to how I understand the zaibatsu of Meiji era Japan operated. The zaibatsu would be large enough to have a pool of qualified workers to run the firm, and small enough that they would have the option to specialize. Family firms would collaborate with each other in joint ventures, and likely also form larger corporations either on a perpetual basis, or in order to complete particular projects. Working outside of one's own family would likely be possible, but uncommon, and probably would more often occur through marriage or on a contractual basis.