IMHO, there is not much of advantage between a 1920x1080 or a 1920x1200 display while gaming. The horizontal view for FPSs are the same, which is where the highest advantage over 4:3 displays exist.
In MMO's or games where you have a ton of customizable UI elements the slightly more resolution of the 1920x1200 display is nice, though nothing earth shattering.
On the otherhand, I HATE 1920x1080 displays for general windows usage. Working with Remote Desktop sessions larger than 1024x768 is a pain. Every extra bit of desktop helps for apps like photoshop. It's a shame that most displays are simply the same panels used in TV's.
My personal gaming and general use preference is a 24" or greater 1920x1200 IPS display. I'm currently using a Dell 2407 IPS display and an Acer GD235hz (23.5" 120hz 3D LCD) on the same PC, and the Dell is, by far, the better monitor. The Acer is really just there for when I want to play 3D games on occasion. Everquest 2 looks pretty phenominal in 3D.