I disagree with the OP.  Grain raises the population cap of your cities.  How is this useless at any point in the game?

And as far as growth goes...you need to *choose* whether you focus on growth or not, by limiting the amount of cities you control and the improvements you build in those cities...I think it's a nice mechanic overall.

Grated it could use some balancing and some more love on the improvement side of things.

But food providing growth is not the mechanic they have set up, nor ought it be that way.

Do you mean growth Sean?  Prestige will be spread across all cities.  Growth bonus is for the city the building is in.  There is already the Tower of Dominion but maybe it is not powerful enough and/or we could have another?

Yes.

It would be nice to be able to affect your prestige more actively, so that the Prestige/#of cities is a real choice between one super city and city spam.

I was talking about City Prestige, sorry for the confusion. Getting +5 to City Prestige from a building with high labor costs and a tier 2 tech requirement would allow one city to rocket past expansionist nations. Building it would not be ideal for an expansionist, who needs to build lots of units. Call it Refuge District and either make it a dead end tech or add it to Administration. Of course it would be nice to have Tower of Dominion and Beacon of Hope add +3 Prestige to a capital.

That way:

A one city strategy would get [(5 FactionPrestige)+(5 From RefugeDistrict)+(3 Tower of Dominion)+(.5 Inn)= 13.5] prestige in the capital in about 50 turns.

A two city strategy would get [(5 FactionPrestige)*(.5 HavingTwoCities)+(3 Tower of Dominion)+(.5 Inn)= 6] prestige in capital in about 50 turns. The minor city would have 3.

A three city strategy would get [(5 FactionPrestige)*(.33 HavingThreeCities)+(3 Tower of Dominion)+(.5 Inn)= 5.17] prestige in capital in about 50 turns. The minor city would have 2.17.

The prestige advantage goes to the small nation, while the larger ones have the ability to train many units. The small nation has fewer upkeep costs per population and can afford more of them due to the high population. This also means more research and thus better technology. From just one Study you would get +20% research to all your research power at only one maintenance. 

That is how i would balance it. 

Thanks for the clarification, probably my confusion as I never think of city prestige, only faction prestige and city growth.

The one city growth problem is a real one and as much as I like the goal of incentivising less spam one problem I see arising is getting enough food quick enough to make it viable (assuming its growth is boosted somehow).  Already a low production city can have trouble building/teching fast enough to keep up with population growth.

The major problem though is unfortunately that the adverse effects of additional cities are currently greater to start with.  That is you suffer a greater penalty going from one to two than from twenty-one to twenty-two.  More spam and less proportionately your major city suffers.  Thus the downside is not suffered currently by pursuing spammed cities with vigour but rather by trying to maintain some sort of moderation.

Monsters are not much of a deterrent to city expansion.  I've setup camp right in the middle of an ogre and a bone ogre and it took them 5+ turns just to attack and destroy the helpless city.  When I create a city two steps from monsters, it's almost never an issue.

To make the world a deterrent to expansion, you'd need Slag/Forest Drake level monsters with some frequency who aggressively seek to kill you.  Like Civ barbarians, who take any opportunity to kill the weak.  There should only be a small chance that a monster doesn't pursue a stack with lesser power.

Definitely like the big +growth building in the capital with lesser +growth from # of cities total.

As city level increases, so will research into techs that boost food. There might be some waiting, but you will get to level 4 before waiting is an issue. Anyhow, they can balance that after they get the basics implemented. 

While the faction prestiege growth makes fewer cities the quickest path to higher level buildings, if you have more than one city, the return for limiting your cities diminishes rapidly.  The hit you take for building a second city is the largest.  If you build a second city, the growth of your capitol drops by 50%.  When you build a third city, the growth of your capitol drops another 33% or 17% of your total prestiege growth.  This doesn't make fewer cities best for growth, it makes one city the best for focused growth.  If you build more than a few cities, you can make up for the drop in prestiege growth with buildings.  And since there is no cost for most of the +growth buildings, there isn't really a disadvantage to going that way.  As has been pointed out already, total production is higher in a multi-city kingdom than in the monolothic ones.  So the only apparent advantage to having only one city is earlier access to higher level bonus buildings and a more concentrated defense, where having multiple cities gives you better production and greatly increases your area of influence, and will eventually allow you to have a much higher population.  As long as you only build buildings that have no upkeep until your economy can support them (or you sell loot, different issue), spam away.

I must also be doing something "wrong".  I go for a few big cities with level 4 & 5 bonus buildings and food works about right.  I research food early on and keep barely ahead of demand, with "gentle rain" as a fallback in case of shortages.  Current system works ok for me.

The food spell is "gentle rain".  Takes Air & Water (unsurprisingly).  Need level 2 or 3 of each, I forget.

I think that he means the city growth, which is based in part on prestige.