Net result is that text is easiest to read with a small number of words per line, and the only way to ensure that cross-browsers, and for all window sizings, is to create a single column.
Here's a page using the full width: http://www.penzba.co.uk/Catastrophe/
That's quite hard to read compared with these:
+ http://www.penzba.co.uk/Writings/TheTeleportingTurtle.html
+ http://www.penzba.co.uk/Writings/TrappingATranscendental.htm...
+ http://www.penzba.co.uk/Writings/EnumeratingTheRationals.htm...
Personally I find those much, much easier to read.
1. Skinny columns of text are easier to scan quickly. This is the same reason newspapers do it.
2. When you're using a fixed-width layout, you're going to look skinny at some screen resolutions and scroll horizontally on others. People are generally more horrified by the latter than the former, so they go conservative and target a fairly small screen size — in that case, 640px wide. Very likely, the people behind the site have a smaller display than you do (though a site targeting 640x480 is still probably aiming a few notches below their own display).
How would you recommend I accomplish that?
Like you said, there's no one optimal layout for all resolutions, and maybe i'm running higher than most people (1440 x 900 on my 15" mbp.. the default). But I would have thought it would be standard by now take into account the screen's resolution when laying things out. Maybe that's too difficult.. I don't know.