You won't be seeing the new 2011 Panasonic Plasmas (GT30, VT30 series, etc.) in stores until the summer, so if your parents want the new TV soon, waiting for the new series isn't in the cards.
I have to agree that the VT25 series is the way to go if you can manage the extra cost. They are, quite simply, the best televisions available right now...period.
CNET did extensive testing on the VT25 series to see if the black levels would rise the way the 2009 models did. They concluded that the black level DOES rise, but only a very, very small amount. So little, in fact, that even after the rise, it is STILL the deepest black level available - even compared to other plasma brands when they are brand new or even compared to Panasonic's other plasma series when they are brand new! So the rising black level issue isn't fiction, but with the VT25 series, it is not something that should deter you from chosing that model line.
I have to comment about two other things though:
1) Screen size is a big deal, IMO. I personally prefer to stick closely to the SMPTE recommendations for viewing distance. The SMPTE recommends a field of view of 30 degrees (ie. 15 degrees to either side of dead center when sitting in the primary seat). To calculate the screen size needed: measure your distance from eyes (when seated in the primary seat) to screen in inches. Multiply that distance by 0.615. That will give you the diagonal screen size that you need in order to create a 30 degree field of view.
For the 54" screen size that is being suggested, you simply divide that screen size by 0.615 to get the SMPTE recommended viewing distance. That works out to 87.8 inches or about 7 feet, 4 inches. That's probably a lot closer than where your parents are sitting. Most people sit considerably further away than what SMPTE would recommend.
2) The Panasonic plasmas do quite well in terms of reducing glare or reflections, but they do NOT do so well in terms of retaining deep black levels and high contrast in anything above "dim" room lighting. "Dim" refers to JUST enough light to read by. Any more light than that, and the Panny plasmas start to look a little washed out and the black level starts to look a little grey. If your parents have sunlight coming in or fairly bright room lighting, do not expect the Panny plasma to look anywhere near its best!
Samsung's plasmas do not have as deep black levels or as high contrast as the Panny plasmas when measured under pitch black conditions. But under normal-to-bright room lighting, they actually retain their black levels and contrast a little bit better. You can also often get a larger Samsung screen size for the same price or lower than the VT25 series Panasonics.
That said, the Samsung plasmas have their own problems, which I actually find to be a lot more troubling. First, the Samsung plasmas buzz - loudly. Some people are really not bothered by the audible buzz, but I certainly am!
Second, after a relatively short time, the Samsung plasmas start to show noticeable phosphor lag. It isn't always so obvious, but if you go from a scene where there is a bright object to a sudden transition where the screen is mostly black, you will see an "after image" of the bright object remain on screen for just a moment. LG's plasmas are even worse in this regard - to the point that I wouldn't even consider recommending them for use.
Overall, I would definitely take a VT25 Panasonic plasma over any other television out there right now. The VT30 series will likely be a little bit better, but not a crazy huge amount and they won't be out until summer. I would be mindful of the screen size and the room lighting. But if your parents can nudge the seating a little bit closer and control the room's lighting a little bit, the VT25 Panasonic plasma is easily the top choice!
Also, the VT25 series is an EXCELLENT candidate for ISF or THX professional calibration. There are options in the service menu and calibration menu (which is only accessible with the use of professional calibration software) that allow for nearly perfect calibration. Most people will be perfectly happy with the pre-set THX mode or with a few minor adjustments in the user menu. But if you really want to dial in the display to almost perfect industry standards, the VT25 series allows for that, which is something that cannot be said for every TV out there
