overview is a very important point here. that's why i use my smaller 22" display for the master and a quarter of my 24" for each slave instead of the other way around.
more than two widescreens are to much to view at once. i use the bigger screen for the slaves so the individual portion of the screen is bigger for each slave (so I can make out details better - or simply so i am able to read the text). i really like the 24" for being able to watch full hd videos but for gaming only i think i would use two 22" screens @1680x1050 so i don't have to move my head as much to see what's going on.

but I think the thread gets a little derailed.
point is: reaction time does only matter for watching fast paced movies/sports or extremely fast games to which i do not count wow. perhaps an avid arena player would differ in his opinion.
refresh rate of any new lcd should be no problem. resolution shouldn't be the biggest point either - except for aspect ratio if you want to use the widely used one screen @fullscreen / one screen @quartered screen layout.