Me and my buddies thought the game wasnt fair at all in it current setup with four, mostly due to Lannister - Greyjoy balance problems. So we came up with our own house rules, thought maybe you guys like it too.
In four player games we play the following houses:
Baratheon, Lannister, Tyrell, Martell.
Not having Stark direwolves in the game is a little detaching from the spirit of the books but hey... Lannister - Greyjoy problem is really annoying.
Other house rules are, all areas north riverrun are off limits including pyke and area around Eyrie. We draw the limit at the river just south of Eyrie and following up west just north of riverrun. So the map basically looks like a square, not including anything north of riverrun and crackclaw point.
We made it so that all fortresses - except home regions (Dragonstone, Lannisport, Highgarden and Sunspear)and Kings Landing - are castles, so they provide 1 muster point instead of 2.
We also placed garrisons on Kings Landing and Blackwater. Kings Landing has a garrison strenght of 8 and blackwater 7. So in early game its very difficult to take these natural places. It gives Baratheon an advantage in position but we think its rather balanced.
It turned out to be a good game, I recommend it to people who find default settings in the manual are not fun.
We are also considering a house rule involving Stark's Roose Bolton card. We find that this card becomes very very unfair in stalemate situations. Stark can use this card every turn if he plays it right, enabling him to use Eddard Stark just about every other turn. Its very unfair. So we make it so that this card only returns one selected card from the discared ones and itself stays down. That however proved a little too weak so we decided to make it two and Roose Bolton stays down in discard once its used. Recommended.