I own a 27", and I am not in the market for anything larger, because my eyes bother me so as it is. But, my next TV (someday) will likely be a High Definition model, and I'll almost have to buy a larger size. But with a sharper picture, it should be less hard on my eyes. My right eye bothers me when I look at any kind of screen for any length of time.
Many men fall into the 'bigger is better' mode that seems so common, esp in the US. To find out what screen size he really needs, it's a matter of doing a little measuring and math, as explained here.