Good Urban Planning
If architecture is the design and style of buildings, urban planning is the design and style of an entire city. While it is true that we tend to reflect on the character of a city by the prevalent building designs, the reality is that those buildings that impress us in a given city are usually in the CBD or similar. The fact that there is a CBD, and an industrial sector, and residential suburbs, and 'ring roads' that connect inhabitants to businesses and jobs, etc. is often overlooked.
Good urban planning is so much more than just making sure that the Eiffel Tower isn't built in the middle of a housing suburb, or that chemical factories aren't in close proximity to farms. Those are the obvious manifestations, but then look at cities like Washington DC and even Canberra where there are wide boulevards leading up to the houses of government in both cases. The memorials are strategically located in a way that reflects their importance to the nation, and there is a focus on quality of life in how suburbs are laid out.
In the case of Canberra for instance, lifestyle is baked into the early city design and many of the older suburbs have walking and bike tracks through them that allow you to get to regional centres without a car if you prefer. Shopping and other necessities are laid out in way that makes it easier to get to and limits traffic between suburbs or regions as much as possible, and parks are laid out in every suburb and region in a way that encourage people to walk or ride as personal pursuits.
Taking that to the extreme, you can go to Transition Cities which are designed to maximise reliance on local resources as much as possible, limiting the amount of transport required to haul goods in and out of the city and wherever possible, establishing a hermetic environment in which everything that is consumed is created locally.
Ultimately, Urban Planning, when done well, takes a philosophy that defines what a 'good life' might look like and bakes it into the zoning and city layout as much as possible so that those that live there don't even notice that the city has been planned with that lifestyle in mind; it's just intrinsically easier to live that way in your city as the assets you need to do so are just... there.
If anything, your architecture can take a back seat to urban planning, not the other way around. Good urban planning would inform the sense of style needed by your architects and inform what is good design by how well it fits into the landscape envisaged by your urban planners.