I live in Arizona as well and I play on an LA based server. I get 40-80ms ping consistently. I think the Seattle datacenter would be similar though, may only be one extra hop, if that.

On Nathrezim we win 90% of WG because of the faction imbalance. Battlegroup is Reckoning - random BG queue is 4-10 minutes usually for Horde. I can't honestly see a bias on battleground results though, no matter how much I thought we sucked, once I installed a battleground stat mod I figured it to be around 50% give or take, depending on the battleground.