$800 in 2009 for a 55" flatscreen is a fairlyland price. I’d love to know where you’re shopping. Although, a 3-year lifespan may indicate a refurb or something.
If you spend $1500 (doable?), you should get a quality TV that does everything you want and lasts.
Plasmas generally provide the best picture for your buck, but do take up more electricity. I’ve run the math and where I live the extra power costs are only significant over a decade or longer.
I can’t recommend 3D as it feels gimmicky and having to buy/locate the glasses seems like a pain.
For plasmas, Panasonic is the best. For LCD/LEDs, Samsung is generally the best.