I recently purchased the Panasonic TH-58PX60U 58" Plasma bout two weeks ago and I am loving it so far. Connecting it to an upscaling DVD player (such as Oppo-981) looks awesome. Also connecting it with the Wii? Don't get me started, it looks absolutely sweet even in SD (I am gonna get component cables for it soon). I was only able to watch SD footage for about 5 minutes and I can't judge my opinion as to how well it looks on the display, but I am coming back from my vacation tomorrow and I will report to you.
Also, for the 58" screen, I don't think you will be benefiting from 1080p at the distance you are viewing your display (12 feet).