I was discussing on an in-game chat about site defenders and income.
I suggest the "oil platform" sites should be defended by sea serpents as the forest sites have elves w/ bonus, swamp pumps have orcs w/ bonus, hills have dwarves w/ bonus and heavy infantry are decently tough when guarding. Currently with fairly evenly spread out sites to different terrains I believe the water and open sites are a cakewalk. While the others aren't real difficult, you have to use a little more intimidation to scare those neutral defenders away.