So I am always annoyed when I play on a Earth map and I can only fit 3 cities on England and only like two on Spain, especially considering how important these countries were all throughout history. So my simple solution make the tiles smaller obviously adding more by doing that and make it so they take up the same radius of 21 of the smaller tiles. Now to make it so you don't have all these tiny cities on your map, when it hits certain sizes you choose the tile adjacent to it in which to expand. With the limit of you can't expand the actual size of the city past the initial 9 tiles.