This was asked by a city manager when discussing where to focus initial CoolTown investment.
The answer for the public sector is obvious: The city-wide master plan.
The answer for the private sector is obvious: The built project.
The CoolTown answer would be both, and more specifically, to build a touchstone CoolTown neighborhood that raises the standards for how the rest of the city could be master-planned, ideally at the same time.
A master plan typically looks at the most successful places in a town that have the highest quality of life and/or economic returns as a model. If a master-plan group should look at inspiring models outside of the town, there’s going to be some opposition along the lines of, “But that’s not our town.”
Build an example of what you want your town to be master-planned as, otherwise you’re simply asking too many people to use their imagination.