Honestly it all comes down to preference.

My preference is to be able to read the type on each client. That said, the ideal setup for me would be 4 high resolution SQUARE monitors for the slaves and 1 high resolution widescreen for the main.

You can rotate two wide screens 90 degrees to get 4 square screens. That means 3 24" monitors. 2 of them rotated to get 4 square regions for the slaves and 1 widescreen for the main.

You might add another monitor just for communication and browsing that also has a TV/blue ray ports so you can watch movies while waiting for the boss mob to die.

lol