Well, if you got the money for one, why not right?
But do make sure to consider where the plasma mount will go to give you the best viewing experience once the plasma TV is installed. Consider lighting, since having the TV against the light will make watching TV a hassle during the day. Plus, you might want to turn off some when you're watching your favorite show or movie without necessarily havig to bruise your shins in the dark as you get your popcorn or soda.
Consider human traffic as well. It wouldn't do to have people passing in front of your TV often, or to have kids always underfoot and nearby.
Consider acoustics too. Unless you're also investing on soundproofing and other sound systems, thin walls do not really make for a great viewing experience since the noise are likely to bounce off walls and maybe wake up people you really haven't invited to the TV time.
Am sure, no matter the size and set-up of the home, there is always one nook there where a plasma TV will fit wonderfully. It might require some furniture being rearranged though.