I've extensively researched the concepts of hub and spoke models for cities and town centers for suburbs.
I think a very effective way to design cities is to have the following:
1. A densely developed urban core that sets quotas on what % of apartments must fall within whatever's considered middle class pricing, as well as a quota for a minimum % of apartments that must be for purchase rather than rent. The former prevents cities from being turned into ghost town banks for the wealthy to park their money, and the latter gives citizens an opportunity to build equity if they desire/have the means to.
Also, there should only he height restrictions on buildings if there's a structural reason for it, not because "it'll ruin the character of the area" or "my views of Central Park will be blocked".
2. Suburbs should be a healthy middle ground between densely developed and suburban sprawl. Living in houses the size of a box isn't appealing, but neither are mcmansions that are 15-20 minutes to the nearest retail center. The concept of strip malls and office parks should be completely scrapped in favor of walkable town centers with multi level parking garages on the perimeters. These town centers should be mixed use, so that people have plenty of options to work, shop, entertain themselves, dine, etc within a reasonable distance from their homes. The town center layout promotes a sense of community and socializing. Suburban towns should have a size limit, and each town should have a light rail station that runs alongside the main road/highway so citizens can easily commute between towns and to the city center without traffic congestion.
When a town becomes fully developed, rather than progressively building smaller and smaller houses to increase density, a new town should be built at the adjacent free land with its own town center. This results in the hub and spoke model of suburb towns that are mini cities surrounding the main urban core, rather than sprawled bedroom communities that have no economy of their own.
3. Between each city should be a low cost and high speed transit option like a maglev or Hyperloop, so that citizens have the option to live in neighboring cities and commute to work in a reasonable amount of time.
4. Zoning should be designed to quickly and easily adapt to growing cities, so that what is zoned as suburban can change to urban as a city grows, and the perimeter of suburbs would grow to account for that. This would occur to a certain limit, and when a city reaches a max size where sprawl is a problem, a new planned city must be built in an optimal place in the state to start the cycle all over again.
In addition to underground subway systems for urban cores and light rail for suburbs, there should be uber style shared car/bus services to fill in the gaps.
As for energy, there should be a heavy emphasis on wind, solar, and nuclear.
The role of regulations should be quality of life protection, not special interests. That means a reasonable minimum square footage for apartments and houses depending on the number of bedrooms, but not a limit on tower heights.