Plasma is on the way out, IMO. And, I wouldn't necessarily use contrast ratios to compare LCDs...manufacturers can determine contrast ratios differently (no standard), and therefore the numbers may not be at all comparable. The best determination is use your eyes in the stores along with the contrast ratios and see if you can actually notice a difference between TVs with different ratios. Some you can definitely tell, others it's pretty hard....
There are pretty good 37" and 40-42" deals out there, or you can go all the way to the high end and pay over $2K. Frankly, spending more than 2 grand for a "better" TV is not a wise decision IMO, considering the obsolescence and new technology introductions coming along. That $2K TV will be replaced with a better, probably cheaper TV, with better technology in a year, so I'm all for buying a good value right now. Have a look at the Toshiba REGZAs (they have 37 and IIRC a 42" that are a great value), also look at the Samsungs, and Sony's....IMO, those are the brands that I've noticed have PQ above the rest for the price. The Toshibas are probably the cheapest, followed by Samsung, and then Sony (always count on Sony to hold the high price ribbon).