Okay, so in my current (and first game) as Earl of Dublin I have reached a point (1356) where I have the thrones of Ireland, Wales and Norway each obtained through inheritance. Ireland and Wales I got early enough that I was able to control my duchies counties; each duke has one county and all other counts are under him in his de jure borders, works fairly well. Haven't had a succession crisis at all.
Once I inherited Norway however, it was a completely different ball game. Norway had a duke that held 7 duchies (York, Herford(?), Orkney, Iceland, and the ones in Norway) This guy was a pain! He immediately revolted and I basically had to fight the entire kingdom. Imprisoned, revoked Herford and left to rot in my Obillite.
This revolt made me think of something though. Even though multiple dukes make it so that when one revolts it is not a big deal, every time I had a succession I was pretty much trying to suck up to all of them. What if I just had a few relatively powerful dukes, (two to three duchies) with counts directly under them instead and just tried to appease those guys. Would it be harder? Would it be easier? I don't really know. I might try that in my next game to see how it goes. Please however post your thoughts on the matter, I am very interested in knowing what the general consensus is.
P.S. One main reason I ask is that the heir of the Duke that revolted has not given me any problems at all (Well besides that he desires the kingdom of Norway) and has made it relatively easy to manage my Norwegian lands because I have not paid attention to them at all.