And as it turns out, those are the exact two models I debated about for a week before finally weighing all the factors I had available against my needs, my viewing area, etc. For about the same money I had a choice of either the VT30 plasma in a 65" or the Sony 929 BL-LED in a smaller 55." I'm sure I'd be happy with either, but in the end it came down to a couple of factors.
First, the living room in my house has a lot of ambient light - not a factor that favors the Plasma. Also, while the Plasma was reported to have a better "off axis" viewing capability, the 929 was said to loose quality off-axis. However, I checked that in the show room and found that, for me at least, the off-axis picture looked great. Both sets have terrific color and very black blacks, so that was really a wash.
Second, once I convinced myself that either set would be great, but that the Sony might do a little better in my viewing environment (lots of light), the other factor that pushed me firmly into the Sony column was power consumption. I did some back-of-the-envelope calculations and determined that the Sony would cost about 1/3 that of the Panasonic Plasma to operate. The Panasonic "might" be a "little" better that the Sony in a head-to-hear picture quality, but for the money I'll save in energy costs alone, it was worth going with the Sony 929.