So if this does go forward and we are just using Major Houses the Players are as follows...

Baratheon ~ Edgeworth
Lannister~ BlackBishop
Stark~ Outcast
Greyjouy~ Fallen of Nine
Martell~ Babbysama
Arryn~ Fiendish Fox
Tully~ Open
Tyrell~ Open

I can see the Riverlands falling under the split dominion of Stark/Lannister/Tyrell or however that works out but we do need Tyrell filled as they are a pretty major player. I don't know if you are open to this Fiendish Fox but we could let "Lysa" grieve and keep the Vale closed to fill out the last major slot. Of course this is all assuming we get Baal back on or another GM.