Well one likely problem is that each of the TVs at BestBuy (I live near one) haven't been calibrated. And in fact many TVs are in 'torch mode' which means they are blasting the colors way more than they should be. This makes the image look vibrant but then the set is over saturated.
Oh, another major consideration for you is what will you be watching? SD or concentrating on HD or DVDs? The reason why this is important is because some sets do NOT display SD well at all.