OK, I've got a bonkers idea, maybe. The thing that crops up all the time about plasmas and LCDs is the lack of true black as against a CRT. So why not mount the display behind a piece of neutrally tinted glass, something like Pilkington Optifloat Grey (with a non-reflective coating), which is the stuff they use for windows. That would reduce the light output of the screen, but that could be compensated for by increasing the brightness and contrast by an appropriate amount - and let's face it, plasmas especially aren't short of available light output. It might decrease the life of the display a little, but is it something that's worth a try?