Also more terrain detail. Instead of just hills, grassland hills, forest hills, plains hills, desert hills, etc.
Maybe the addition of climate zones. As a result, grassland in a temperate zone in temperate grassland, Vs. tropical grassland, with different food production, resources, etc.
whatever the zonecolder than temperate is (sub-temperate?) would be less productive in food
Also another type of tile: rocky grassland. less food than plains, takes longer to irrigate, more food than hills.
that way you don't have to put 'plains' in the lowlands of say, New England, to represent the difficulty in farming areas like that as opposed to more fertile areas.
