I'm no self proclaimed expert on TVs, just know what I like and don't like...
My impression is that LCDs are better choice if you watch a lot of sporting events because they tend to be brighter.
My impression of a good plasma is that it handles Blacks better and more suited if you watch a lot of movies.
My boring story about HDTV, is that when I used to support the Information Age exhibit at Museum of America History in the late 90s, and they had on display a prototype tube HDTV which had a truly amazing picture. And every HDTV LCD or Plasma I saw after that paled in comparison to it, until I saw the Pioneer I own today and the reviews of that TV at the time backed it up. The only HDTV that came close were those 250lb tube models Sony used to sell. Of course try convincing ones wife to let you buy a 250lb TV
Also as far as what size to get, it's best to get buy off from the significant other before proceeding