I really do think that Pendragon would be the best RPG to experience a Game of Thrones (Song of Ice & Fire) feel. Personalities are so strong in the characters, and many do foolish things simply because it is their nature. The trait system and passions of Pendragon would probably best represent this. (I discussed some of these thoughts over the official KAP forum too.)
I've thought doing a conversion of Pendragon for some friends who love Game of Thrones and D&D, but abhorred Arthurian Pendragon. I think Pendragon's a great fit for really recreating the books, assuming some changes in the starting passions, traits for each culture, and the religious traits (the Seven, Old Gods, Drowned God?). I'm also tempted to take out the Chivalry bonus. Overall, changing traits and passions to reward having a strong personalty, rather than a chivalrous one, would be my goal. I might even double or triple high trait scores for Glory, just to reflect the strong and stubborn personalties in the books better (e.g. seems like Cersei has a high lustful and Tywin a high Prudent). I think Love family, Loyalty, etc. should also be more random, rather than starting universally high as in Pendragon (I mean Roose Bolton's Loyalty(Liege) seems pretty low to me). And perhaps with a corresponding toning-down of the penalties for failing a passion roll, maybe it should just decrease the passion on a fail. I think I'd also be pretty generous about handing out Directed Traits too. I really like the idea of using Intrigue or Orate to intentionally invoke another character's trait (NPC or PC) too. I think would be pretty generous about empowering those skills in verbal disputes.
As far as household income, I think a simple "narrative" system like that in Book of the Manor would be best (i.e. just tell the players how much money they got). In the rough-and-tumble wars of the five kings I can't imagine having time to go back and tend the dovecotes. Just give the knights income for accomplishing things instead: great you captured an Lannister knight, now you can afford to buy a new Charger and hire some bodyguards so you don't die in the next battle. That sort of thing. Another option would be having a monthly Winter phase, more like a week, just to keep things apace. I think then you could have the events in the books going on in the background, with the PKs participating in whatever manner seems appropriate depending on which House they're loyal to. If you want financial management to be a bigger part of the game, make the PKs have to seek out rewards from members of the Great House and just give them large holdings. E.g. you gain Harrenhal for defeating the Mountain, that is worth 60 libra/gold dragons! Then allow them to buy retinue, new fortifications, equipment off the year 530+ list. This would give plenty of incentive to backstab other knights, etc.
I think it would be worthwhile to look into the old books for KAP like Saxons! or 4th edition (I have neither) to check out alternate, non-standard virtues/traits for Game of Thrones.
I think it would be worthwhile to look into the old books for KAP like Saxons! or 4th edition (I have neither) to check out alternate, non-standard virtues/traits for Game of Thrones.
I do want to say I have investigated both the d20 Game of Thrones and the current dice pool Game of Thrones. Both look horrible. I hate social "combat" challenges as making no sense and being meta-gamey. It's like D&D, why not just talk it out with some basic "guidance" on the dice like a reaction check or skill check possibly inflaming a passion/trait as in Pendragon. So much simpler, so much more intuitive, and players (not just characters) get to really try and convince people of what's going on and get rewarded for intriguing themselves. Many of the fans of these games like the ability to play children or characters like Septons. But what fun is it to play a child like Bran or Rickon or a nun? If you're a non-knight, play Tyrion or Catelyn or someone for god's sake, characters perfectly reproducible in KAP stats.