The solar system beyond Saturn is a vast and mostly empty region of space. Points of interest are separated by hundreds of millions of miles. Distance and difficulty of travel keeps most people from bothering to make the journey. Nevertheless, there are people here. Uranus
Uranus has several small aerostat habitats and a larger number of automated stations, mostly devoted to extracting, processing, and shipping Helium-3, the extremely valuable isotope used for nuclear fusion by most of the solar system. The planet has no primary government beyond the owners of the various aerostats. There are fewer than 100,000 people on Uranus or any of its several moons. The Uranus planetary system is a bit of a lawless frontier, excepting the rare times when the Saturnian Navy dispatches a patrol ship to "show the flag".
Neptune
Neptune's largest moon, Triton, is the basis for human settlement here. Triton was settled in the late 2300's by Chinese dissidents from the Saturnian Federation, including naval mutineers who resented the Russian cultural influences among the "First Families". Rejecting the inner system for a variety of cultural and social reasons, they instead journeyed to Triton. After traveling here, they established their own Helium-3 mining operations on nearby Neptune. They managed to establish cordial relations with the Belt League and several Wild Belter clans, allowing them time to grow. Over the last century and a half, Triton has established a small but powerful navy, dedicated to enforcing its territorial claims on Neptune, its moons, and the various Trojan asteroids orbiting with it. Roughly five million people live on or near Triton, under a stable but somewhat corrupt republic which survives by selling He-3 to pretty much everyone but the Saturnian Federation. Triton is currently the only place in the Solar System where Mandarin Chinese is spoken as the primary language, a result of ethnic tensions among Saturn's original population. Recently, Triton has expanded out into heavy industry and commercial shipbuilding, competing directly with Chandra for the small market for ships among Belters.
The Kuiper Belt
This seemingly endless region of small icy bodies drifting around the sun at 30-50 AU is home to a large population of transient ships owned by the Belters. They travel from chunk to chunk, prospecting for rare elements, and processing frozen gases and organics. Permanent Belter settlements have been established on Pluto and Eris, which are used as safe places to resupply, rest, and meet with other Belters. Permanent settlements have been established out in the Kuiper Belt, serving as way-stations and ports for the large numbers of independent belters and other drift communities. "Longway Station" is the largest, with over 25,000 permanent residents living on Pluto. Second in size is "Sacred Chao", with about 15,000 people calling the dwarf planet Eris home. Each of these stations is considered a "City" of the Belt League, but their distance and isolation mean that life there is much wilder than in the habitats of the Main Belt.