Aaaand this is why I switched to first a tiling WM, and then to OSX for its intuitive 4 finger swipe workspaces.
Till that switch I was a multi monitor junkie, but after 3 monitors it starts getting bad for your neck, bad for your eyes (with all those monitor backlights burning your retinas) and you also need humongous desk setups.
Nowadays it's just one big monitor and 4 finger swipes.