Towns are a good addition to the game. On paper at least, they can remove a lot of city micromanagement. That hinges on how much gold you can get. Since towns are major sources of gold, the more towns you convert into cities, the harder it should become to convert the rest. I don't think the game is currently balanced well enough to ensure that this is true beyond the halfway point of Exploration, and I think it's possible to even reach that point in Antiquity. It seems like, at some point, gold just becomes too easy to come by as you get high-adjacency gold buildings up and gain access to leader attributes, policies, etc. that provide maintenance discounts.
In terms of strategies, here's what I have. You need to keep in mind that a growing town provides more or less just the following: resources, gold and happiness. Before it can be specialized, it keeps all the food that it generates, and it's very hard for towns to generate meaningful amounts of science, culture and influence because they don't usually have access to buildings that provide those yields. Of the three benefits that a town provides, the most significant is the resources, so your primary focus has to be on collecting as many useful resources as you can. Gold is much less significant, at least while the town is still growing. Happiness is still less significant, but it doesn't mean you want to neglect it. At the very least, you don't want your new towns to tank your happiness by going over the settlement limit. Consider a scenario where you're looking to settle a town that can get access to three copies of sheep. Sheep is a good resource, but you should remember that each copy provides +2 production and +2 happiness. If this town makes you go over the settlement limit of, let's say 6, it will result in a penalty of 35 happiness, or -30 happiness if you exclude the -5 happiness in the town itself. That means your net gain is +6 production and -24 happiness, or potentially even worse if your cities don't have empty resource slots. That's not a trade-off I'll often make.
My rules for settling towns are like so:
- Settlement location selection is all about resources. Happiness penalty for settling off fresh water is almost never significant enough to deter me from settling with the aim of collecting the best resources.
- Early towns will eventually become cities. Make sure to give them plenty of space.
- Avoid over-settling. The happiness penalty that comes with it is usually not worth it.
- Focus on growth in young towns, with the aim of switching out of growth tiles once they're fully developed.
- Food buildings like granaries are useful in towns as growth is half-priced, and so are resources like dates that give food to towns.
- Buildings like brickyards are useful for eventually kicking out farmers to send them down to the mines.
To elaborate on the last rule, consider the following scenario: in Antiquity, replace a 3-food farm with a brickyard in order to relocate the citizen to a 3-production mine. If this town already has 4 other mines, that brickyard represents marginal income of 7 gold per turn. If you put the town to mining focus, it goes up to 12 gold per turn. The brickyard has a base cost of 220 gold, which means you break even in 19 turns. To put that into context, if you built the Pyramids (base cost of 275 production) in a city that can immediately get value from it on 8 tiles, and if you assumed that 1 production were equal to 1 gold, it would take you 18 turns to break even (275 / 2 / 8 > 17).
