Some basic stuff:
Used to be that plasma TV's simply had a better picture. Now, with the advent of high contrast, high refresh rate LCD TV's, the gap is pretty much closed.
Reason I went with LCD is simple. They use a ton less power than plasma, and now the picture is just as good...to my eye anyway.
The 1080 resolution is going to be, if not already, the industry standard for high def TV. Depending on what your signal source is, you must get a HD package via satellite or cable to see the TV at its best. However, over the air HDTV, via antenna is free, as long as you're in range with your house top antenna. And believe me, high def "best" is pretty darn good! But, remember, not all TV is high def...and slick marketing types like to get customers to believe that digital TV and high def are the same thing...they are not.
Refresh rate. An old knock on LCD TV's was that in fast action, like sports, the picture would blur around the action. Then they came out with a 120 hz refresh rate, which has dealt with that problem. [I see now that they're touting a 240, too, but that seems to me to be way ahead of the techno curve. FWIW, "normal" non-HD TV cameras operate at 60 hz, I believe, in that case the point is moot.]
All built in speakers will be relatively disappointing, which is why most people run the sound through a surround/AV/multimedia set up.
If you want to check out thousands of customer reviews, go to newegg.com Bring up the TV section and you'll see tons of reviews on just about all the popular models. It'll give you good starting point.
Having said that, I settled on the Samsung ToC 46" Absolutely amazing picture quality.
Hope this helps you in your search.
Len.
BTW, how'd your dogs do last Fall?