Entirely up to you if you want to 'mirror' your kingdom in way of amount of settlements and whatnot, but this is my plan for Estarion:
City:
There will be just one in the kingdom, and it will be a walled, well-fortified affair made of some classy-looking material of Blast Resistance 30 (most likely Stone or Iron Blocks with the occassional Gold Block thrown in to break up all the gray). As yet it is unnamed, but it the pinnacle of Estarion, and will likely be found in a very defendable position.
Settlements:
I intend to have 4 settlements in total. (well, City +4)
* 2 will be randomly placed in the kindgom and will comprise of mainly Blast Resistance 15 materials (prob wood planks) with spatterings of blast resistance 30 for things like roofs (prob cobblestone).
* 1 will be secluded, surrounded by trees and will be hard to find. This will have access to the start of a mine, but won't be very dug out - its for players to mine 'properly' without the aid of spawnings etc.
* 1 will be a coastal village and will be made primarily of Blast Reistance 15 materials. It'll be important due to its location, being the main defendable position from sea-based attacks and also access to water-ways
Geography:
Generally speaking, Estarion is going to be woody / hilly with the occassional mountain range or beach. It won't have any desert areas, but I intend to snow in some of the 'higher' areas such as mountaintops etc.