patience you padawan its up now
yeah looking at it now the max number of count vassals a duke can have too small, there would be huge chunks of the Reach and Rock that wont be able to be bannermen of a duke level High Garden or Casterly Rock
Wait, what kind of limit is that? I've never heard of it before. Presumably you'd be able to make things easier by, for example, folding all of Oldtown's vassals into their demesne instead. It would mean less in the way of playable houses, but the fidelity to the books would be a lot better.
Also worthy of consideration: What about a scenario set before Aegon's conquest, when there really
were seven kingdoms? It would involve a lot of guesswork and speculation, obviously, but it's probably the age of Westeros's history that would translate best into CK. For bonus points, give Aegon a "Dragon" trait that gives him boosts to Martial and claims on all the thrones.
Also, now that we actually have
a map of Essos (or at least part of it) what about expanding the game map? It would give the Westerosi somewhere to flee to, and make modeling the time period of the books a hell of a lot easier.
EDIT: Actually, come to think of it, the Free Cities were apparently offering to make Aegon the ruler of a new Valyrian Freehold, and he seriously considered it. It would be interesting to do both - make a pre-Conquest scenario with Essos, and present Aegon with a choice-by-event: join with the Free Cities and become the ruler of a new Valyria, or swear to do what no king has ever done and get free claims on all the Seven Kingdoms.
While I'm on the subject, other event chain suggestions: breeding and raising dragons, tourneys and mystery knights, abducting your lover from another court, confronting the guy who kidnapped your sister, and executing rivals who are also your vassals (has the bonus advantage of letting Robert finally finish off those goddamn Targaryens)