I went from a 16:9 back to a 4:3 when the opportunity arose. I just got tired of always stretching or zooming the 4:3 content, and I hated the grey vertical bars. I got a Sony HS30 that does a vertical raster squeeze for HD and progressive DVD content. Since the width of the TV was my limiting...
Al_M, You should also consider the Sony KP43HT20 4:3. It does the 16:9 squeeze for 1080i HD and 480i/480p DVD so it gives you the equivalent of a 39.5 inch widescreen TV. It also does an excellent job with standard TV.