Well, having a single wide monitor means I move my neck very little from side to side (maybe 15 degrees each side?). Even my old (60) eyes have no trouble viewing the edges.
We can visualize some geometry here using some highly appropriate ASCII art (-, /, and \ are screens, * is the user):
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*
vs.
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/ \
*
The first one requires you to move your neck much more than the last option; it also provides a better peripheral view. I have a corner desk, so my setup looks like:
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/
*
More or less; I also have a chair that pivots, so I can change my focus quickly without moving laterally. What is really painful is when, to reduce horizontal span, the monitors are thrown into portrait, then you have up-down neck strain...which is very painful! I actually decided against another 24" as my second monitor for this reason (I have a secondary 21" wide screen in portrait as my secondary, nice for reading PDFs and email).
I would prefer to have one wide monitor, but with a curve.
I'm not sure. I have a 30" widescreen at work I primarily use in isolation (the laptop next to it is pretty puny by comparison), and dualies in a laptop-monitor-monitor arrangement as in Example 2 at home.
The single monitor is wide and requires much scanning, but I think I prefer the experience to multi-monitor window management. I just end up not using the far right screen except in the most necessary situations (design + code + browser)
I really don't see how the second option change anything for your neck, on the opposite it is pretty clear on the picture that it won't change.
However the second setup will allow you to be perpendicular to the screen on a wider area, reducing the average angle between your eye and the screen surface. It might be more comfortable for some people from a perspective point of view, but not for the neck.
