[Suggestion] Hazard Range
In Civilization 4, you can pretty much build a city wherever you'd like and you are limited only by the geology of the terrain. There may be a few barbarians here or there, but even raging barbarians are a pushover.
In Elemental, I would like to see Hostile NPC's and dungeons be a as influential on where you place your cities as geology. What I mean by this is that many hostiles would have a range of hostility, and the closer your are to them, the greater likelihood they will attack you and in greater force. So on the strategic map, you would toggle a little "hazard" button that would color the landscape to represent the "hazard rating" each square is subject to. When you destroy dungeons or or other hostile entities that are contributing to that hazard rating, the color goes down in intensity. Also, until you explore the surrounding area, you aren't aware of what the "true" hazard of a square is.
So basically, when you are planning on where to plop a city, not only do you have to consider the resources of a location, but you must consider whether it is safe. You would basically have two modes of spatial expansion: you could either conquer other kingdoms or you could clear out hazards and build new cities. In this schema, hazards would be highly formidable, sometimes even neutral, non-sovereign opponents (an underground city of undead, tribes of trolls, etc.)