At the moment most settlements are a mixture of agricultural and industrial centers and so the city-screen mostly gets mixed up because of the split of people working inside and outside.

My idea is to separate the agricultural and industrial aspects.

1. Agricultural settlement
Will allow to harvest the common 3x3 squares. It will have a warehouse to store harvested ressources and food.
Basic city tile has to be worked to receive ressources from it.
City-Screen shows mostly the 3x3 tiles and stored goods ... Limited population.

2. Industrial City
Size 1x1.
Does not allow to harvest any tile.
Does not receive ressources from basic city tile.
Is dependent from ressources from surrounding Agricultural settlements. (Food, Ressources,...) by traderoutes ...
Allows to build more advanced buildings like University, factories, ship yards.
Allows to build arbitrary multiples of these buildings to allow arbitrary number of workers to process ressources ...
City-Screen can concentrate completely on the buildings inside the city since the surounding area is no longer to be displayed.

3. Trade-Network
To make transport-costs interesting, the relation of ressources to final goods should be 2:1 .... So the player has a reason to establish more than one city to minimize his transport-costs ...

To survive the starting turns with no settlement, the player needs some Food storage to start with ...

The setup would be a little bit like Imperialism 1 but Col-Style ...