On my NEC 24", 1920x1200 was just too small for me. The combination of high-resolution with low pixel pitch just made all the text and icons in Windows and applications impossible for me to read unless I sat way too close. After a few minutes, I'd get eye-strain and headaches. I spent hours playing with Windows DPI and font size settings, but they don't really work unless you're OK with the fact that all your menus are screwed up, some icons are blurry, and layout/format problems abound in Office and other apps.
On my Planar 26", 1920x1200 is perfect, because the physical size is larger, and the pixel pitch is higher. Everything is fine at default, with no need to adjust DPI or font size. I get all the workspace of 1920x1200 without any of the pain. I can sit at a reasonable distance and even see the details in the Vista micro-icons. Its much better than even 1600x1200 on a 21".
So IMO, 1920x1200 on a 26" or 27" is great, but any smaller than that and I just can't hack it. I'm in my mid-thirties and my eyesight is not what it once was, so others may disagree...but I don't blow all this money on video cards and LCDs so I can't read anything or see small icons or fine details in graphics.