This is where the use of extra displays gets to be serious fun. There are a lot of ways that extra displays can be advantageous. Having one screen for the game and another screen showing something else like the internet or whatever is one way, but the main focus here is how best to enjoy games stretched across multiple monitors. In this post I am going to look at the advantages of both the dual screen and triple screen approaches I will use my Paladin from World of Warcraft to demonstrate how they differ from each other.
Obviously the triple monitor option is superior to the other choices. I have heard that there is a way that your player can be made to be a little more to the right or left in dual screen mode, but I have yet to see someone accomplish it. In this instance, assuming that you could do it, it would appear this way:
Dual Screen Display (center shifted to the left)
This version of the dual screen is, in my humble opinion, superior to the first dual screen example.. The left(or if you preferred the right) screen is the center focus and the right screen serves as what could be considered you right peripheral vision. In the absence of a third screen it takes some getting use to. It is, basically, the triple monitor system without the left monitor.
Dual Screen (stacked)
This configuration, I would think, would be reserved for flight simulators or something really unusual. I am not going to bother showing three monitors stacked because that would just be silly. I will leave it to you to decide what works best for you.