It depends on what you want to do. If you want to be a King you need to keep as many holdings in your personal desmesne as possible so every county counts. Plan on marriage to heiresses in the kingdom you want to own or Crusade for more land in Iberia. You will have to declare Independence eventually from England if you want to create a Iberian Kingdom.
If you stay in England see if you can inherit the Duchy's of Somerset and Kent that way ALL your holdings will be connected.
Thanks for the answer! It's my first game, so I'm just looking to learn the ropes, I don't think I'll actively go after a kingdom. I can't get the Duchy of Somerset because it's owned by the king of Castille (English line that crusaded in Iberia then lost the Kingdom of England). Every time I try to claim the counties I have a forged claim on, they land on me with massive numbers that I can't possibly match. This is the case even when I declare war when they're busy fighting, since sieging takes so long. I've had a few close calls with not getting myself imprisoned and getting away with a white peace. They also have agnatic law, so I can't marry my way in.
But I eventually tried a different tack. In one generation I had a stroke of luck - four sons and a few neighbouring dynasties with daughters at roughly the same age. It was great, I was married to the heir of Lotharingia (though sadly that marriage produced no heirs) and all my five kids were dukes or counts. Though this had problems of its own - I had a lot of trouble finding worthy family members to give my excess demesne with or make strategic marriages because all of them, even the baronies, moved to their own separate courts.
1) What long-term advantage is there in a patrilineal marriage to a rival house? It seems like all that does is to give that family a bunch of fresh blood.
2) How bad is having a larger demesne than you can have? Should I be getting rid of them asap, or should I hold on to them until someone suitable comes along? I have 11/7. As I mentioned, I'm not expansionist this game, but I do want to end up with a nice power base.
3) I'm still not entirely getting the succession system. Sometimes they change for no reason (resulting in me wasting an heir on some minor noble who's a dozen candidates away from the seat), and I saw a younger son being an heir once over an older son, when I had agnatic-cognatic primogeniture.
4) The game ends in 1453, right? It's now about 1360 in my game.
