I've had my 42" Panasonic plasma for over 5 years, and there has been no problem with screen burn. Screen burn was an issue with first and second generation plasma TV's, we are on fourth and fifth generation plasmas now. They addressed the issue early and included a variety of fixes over the years. I believe my tv uses image shift, where the image is shifted left, right, up, or down an imperceptible amount. At this point screen burn is nearly an old wives tale. The 1 way to make sure you avoid it is to make sure you have your picture set to full screen, if you
always watch in 4/3 with the black bars on the sides you can get ghost images of the black bars. But you would have to leave your tv on 24/7/365 to achieve this. The other
old concern was the network logos in the corners, but the networks move these around some and change them on occasion, you would have to watch the same channel 24/7/365, and image shift should also prevent this.
As far as brands to research I would highly recommend Panasonic. And when I say highly I mean
HIGHLY recommend. Like i said, I have had mine for over 5 years and love it. I also have 2 friends that own the same model year, 1 has the 37" and the other has the 52". Mine is the TH-42PX60U
http://www2.panasonic.com/consumer-electronics/support/Televisions/VIERA-Plasma-HDTVs/model.TH-42PX60U The biggest con I would say is the power consumption, if you watch a lot of TV it will get you in electricity. You also get glare if there is a window or light source in front of the screen. But if you are in a dark room watching a movie, nothing beats the depth of the blacks. New LCD thinks it has deep black but it doesn't. On a plasma tv black is black. Although new LCD's are better than old the blacks are still a little gray, I always thought of it watching my TV from behind a window screen.