My most recent project, our client assured us that 1280×800 was the right resolution for them. Knowing their user base, I kept asking if they were certain that was right and they kept saying yes. Of course, after we finished the high-fidelity prototype, they came back and said we needed to scale it back to 1024×768. Pain in the a**. Practically had to redesign the whole thing, especially because they were adamant about certain things fitting on one screen so they could see data at a glance.

–mcb

I’ve used a photo gallery web app, Wipha, that has a fixed column width (for picture thumbnails) but chooses the number of columns to display in the grid based on the width of the window, thus requiring only vertical scrolling. I wonder if this would be a reasonable way to handle fluid width with text – set the appropriate maximum readability width (since we know people can’t follow excessively long lines), and then columnize as needed to fill the appropriate % of the total width with the primary text content. The main problem I’d anticipate there would be multiple vertical scrolls requiring to jump from the bottom of one column to the top of the next. You’d also want to avoid breaking sentences across columns/pages, I’d think.

There are still issues with the line-breaking code in many browsers, where if you fail to specify an overflow option your layout will explode when confronted with single tokens that are longer than an entire line (perhaps a long in-text URL, for example).

You currently might have a more savvy audience, but you may want to target other audiences that are less savvy.
1024 X 768 according to wikipedia looks like it would be good.