That leaves us with Arryn, Baratheon, Lannister, Tully and Tyrell. I eventually plumped for Tully, partially because their banner men are arguably the best described in the novels outside of the Northmen, and partially because the Lannisters are too irritating, the Arryns too meek, and the Tyrells too obsessed with plants.
So far, having begun this project exactly one year ago today (thanks to some useful birthday presents from Cocklick, Dr. L and DB), I've managed to paint all of two knights in between finishing my Blood Angels, continuing my Tau and Red Corsairs forces, and painting the occasional Strike Cruiser. Here they are below. Once again, I'm still learning how to use this digital camera so that things don't immediately turn out shit.
Here we have the battle standard bearer of the Tully army. The knight himself is from House Mallister. I lightened the purple somewhat (dark purple is a pain to paint), but the silver eagle came out quite well. Obviously, the banner he is holding belongs to House Tully itself.
This is the army's musician, a Vance from Atranta. The shield proved too tapered to include the green dragons and white towers, but they appear on the sides of the barding instead. 
 There's almost certainly a technical term less vague than "the sides", but I can't remember it right now. Come to think of it, is "barding" even the right word. Christ, how do historical re-enactors cope will all this crap?