I've been really happy with the Samsung plasma that I have (my folks have an identical one that's a year older). Plasmas are cheap, and IMO they have the sharpest picture. The downsides are that they run hot, they're heavy, and you can get glare and reflection if you don't stick it in the right spot. I've heard they only last about 5 years, but that's just crap I read on the interwebz and I've never had it confirmed. But if you think about it, it'll be obsolete in 5 years anyhow, right? Also, the last tube TV I had crapped the bed in a scant 3 years - and it was a top-o-the-line Phillips-Magnavomit.
Reconsider the 1080p, the 120-240Hz, and maybe even the size. I looked long and hard at 720 vs 1080 and, frankly, I couldn't tell a whole lot of difference - even on a 50" screen. Also, I think the super-high refresh rates are a gimmick - your eyes won't be able to tell the difference. When I was first browsing at Fry's, they had a 42" stuck right next to a 50" and, of course, the 42" looked puny and pathetic next to its big brother. But once I got the 42" home, it looked PLENTY big. Not sure how big your space is, but 50" may be overkill if your sitting 10 feet from the TV. Also, prices seem to ratchet up at the 50" level. Just sayin...
I think most units on the market have RCA inputs, but you should really look into a receiver with HDMI capability - all digital, and it really cleans up that rat's nest of wires behind the TV. Onkyo has been darn good bang for the buck for me, my folks, and a couple of other friends that decided to upgrade.
The Wii is neat and all, but be aware of the fact that you have to buy the component video cable from Nintendo in order to get the best quality. Even then, it's only 480p. It's cute and all, but you should really just get a PS3 and GT5 - at least you can tell your wife you got her a BluRay player.
As for reviews, I usually poke around on Amazon and CNET to see what looks good. The Samsung was way up CNET's list when I got mine (admittedly, over a year ago).
You'll probably end up buying new furniture to go with your new TV, so you might as well plan to go balls-out and upgrade your whole system.