I was at a Best Buy around X-mas and was looking at the plasma TV's (I have a 15" Sharp for my desk and love it) as I was thinking about a new and bigger one for the family room. Was approached by a salesperson who didn't seem to be a BSer and he told me one of the things to look for when buying a plasma is to go around and feel how warm the top of the TV was. I felt several different ones and there was a noticeable difference in a few. He said the ones that stayed the coolest were the ones that have the least problems. He said heat is the worst things for plasmas as some people have put them in somewhat of a confined area where there isn't a lot of air moving around it, and that is a main reason some of them fail. If you go to big retailer, feel how warm the top of Plasma TV is, and you will see what I am talking about. Whether this guy knew what he was talking about is another thing, but he wasn't your typical "used car salesman"(LOL) IMO. Considering they don't work on commissioin there, I tended to believe him a little more.
He did say for the money, the Sony HDTV was the way to go. Takes up more room, but the picture seemed to be just as good.
Good Luck whichever way you go.