The few ways you could do this:
The 7 kingdoms:
Stormlands, Reach, Westerlands, North, Vale, Iron Islands, Dorne.
The 9 great houses:
Stark, Lannister, Greyjoys, Baratheon, Tyrell, Tully, Martel, Targaryen, Arryn
Clash of Kings (Set midway though the second book, right after Renlys death):
The North, The Iron Islands, The Lion, The Flaming Stag
The above 3 maps are strictly Westerors, The following 2 also contain Essos, and contain spoilers from the other books.
A Feast For Crows (Set at the end of the 3rd book, contains spoilers)
The Iron Islands (Pyke, Great Wyk, Deepwood Motte would be their scs)
The Lion (Dreadfort, Casterly Rock, Lannisport, Kingslanding and the Twins) 5 scs, but rather spread out and enemies on all sides.
The Flaming Stag (Castle Black, Dragon Stone, Storms End and White Harbour)
House Martell (Sunspear and Yronwood) Only 2 scs to represent that its a smaller power.
House Tyrell (Highgarden, Oldtown, Ashford and Bitterbridge)
The Targaryens (They would have Pentos, Mereen and Astapor)
The Slavers (Volantis Yunkai and Mantarys) they represent alliance of slave states at war with Meree. Doesn't include Qarth because Qarth would be off the map.
The Dothraki (Vaes Dothrak, South Dothraki Sea, West Dothraki Sea would be scs)
The Free Cities (with exception to Pentos and Volantis) would be scs occupied with neutral armies.
Dance with Dragons (Varies between the middle of the 5th book and teh start of the 6th with some balance adjustments and assumptions):
Flaming Stag (Controls the North)
Iron Islands (Controls the Iron Islands and The Reach)
The Targaryens (Controls Dorne and Essos)
The Iron Throne (Controls the rest of Westeros)
The White Walkers (Controls everything North of the Wall.