I think you can never have enough settlement scenarios, and a rather cheap way would be to introduce something like a map generator:
So you click "Create new Map" and then have a menu similar to the "Landscape" panel in the scenario properties window from CRs Developer Mode, just more advanced. You can set the materials to be used, the weather, goals and rules, starting equipment, and landscape type (e.g. sky islands, caves, mountains, ...).
Most of this is already in CRs Developer Mode, so maybe you could take this as a starting point?
I remember how much fun I had in CR creating a map in Editor Mode, throwing in some Ozarks and killing them with teraflints :)