Went through that myself a few years ago when I bought my HDTV.
It's true, you generally want to avoid lots of veiwing in 4:3 mode. Most current HDTV's have features that reduce the chance of burn in these modes (such as scrolling), but lot's of 4:3 veiwing still promotes uneven phosphor wear.
Stretch/Wide mode features have gotten so much better so much better since my set was production, but at the time my Sony had the best stretch mode out there. That's all I use for 4:3 veiwing. As far as I know, Sony still has killer stretch features.
One thing that Sony did that the others were not doing at the time was stretch more toward the edges of the image and less in the middle. Since focal points of images tend to be around the middle of the screen, less stretch there prevented minimized things like faces looking wide and short. On my set, you don't even really notice the stretch with most program material.
Whatever your choice is in a widescreen, you might want to do a little research here:
http://www.avsforum.com/avs-vb/Here:
http://www.hometheaterspot.com/index.phpAnd:
http://www.audioreview.com/Just to see what people are saying about the sets you are interested in.
D