There are a lot of different options for DLP/LCoS. The new JVC's and Sony's are pretty kick ass. The Sony doesn't have an old school color wheel like the Samsung either. The new XBR2 is awesome, but more than what you are looking at spenging probably. They do have a 70" though!
Since it is for your dad and he isn't the one doing the research, he probably isn't into HD anyway, so a plasma would be fine as long as the doesn't burn anything into it. I am going with LCoS or DLP, unless something better comes out soon. Probably buying in the spring.