I like the Birthright D&D Expert rules, where it had Dominion rules; it would say 1 24-mile Hex would make you a Baron, 2 would make you a Viscount, etc, and it had things you can do in 3-month turns as a Dominion ruler.
I wanted to do something similar in Rolemaster. In "Castles and Ruins," it states that a castle can control a 10-12 mile radius area; beyond that, your control is lessened because your knights would take more than a day to make a round trip to the castle. Then there is a chart that gives you the taxable population per Acres (and also gives suggested noble title).
And that's where I'm having a problem: that the scale is in Acres. A Town is approx 1,250 acres; a small city, 12,500 acres, a country 12,500,000 acres. The chart indicates that a Baron would own 12,500 Acres (a small city???). Even so, unless you have a campaign map scaled to 1 or 2 miles, I can't see how one can manage it this way.
Most people (I would imagine) has their campaign map scaled to 24 miles per Hex, making each Hex is 319,251.2 acres. If you make a PC a Baron you can't just give him ownership of a Hex -- the area of control would be too large; according to the chart, owning 1 entire 24-mile Hex would make him a Prince (owning a large Territory).
It's a bit fustrating, because I know that most campaign maps have entire countries composed of many, many 24-mile Hexes; using the Castles and Ruins, there would be hundreds of Counts, Dukes, Barons just in one country!
Is it easier to just scale of the charts up from Acres to a square miles? Has anyone done something similar to what I want to do? Maybe I'm looking at this the wrong way?