It looks like all the monitors just need to be the same resolution. It also looks like at least one of them needs display port. I just mention AMD over nVidia because they are credited with having better multi-monitor support.
I wouldn't worry too much about 120hz with multi-monitor, you'd probably need a triple video card setup just to get the frame rate over 60 in most games.
If I were going multi-monitor, I'd go with 27" 1920x1080 just because it's all about filling the field of view, and trying to maintain frame rate.