I use two 1680x1050 monitors. I've got 2 1680x525 regions on the first monitor, and 3 1680x525 regions on the second monitor. The 3 on the second monitor overlap. This allows me to easily see if I've lost followers.

I would love to be able to have one monitor devoted to the leader and the other to the followers, but the PIP switch delay caused me too much grief, and this compromise works ok.