@xahlee The more real estate the better, until you have to actually turn your body. I work with three 24" narrow monitors and I find I have to flip the third one up to vertical orientation so I don't have to track too far back and forth. It's surprisingly useful for reading long documents and managing busy email though and then you have the other two for real work
am not sure about that. but also, if you use autohotkey, one can make it more efficient than any linux tiling manager.
See also, my article
Why Tiling Window Manager Sucks (xmonad, ratpoison, dwm, …)