Answered your own questions! You're on the right track I think.. if viewing angle is important, LCD is going to be a horrible experience. If the Panny is working fine... keep it, God knows that if the gf ever leaves, she's taking your plasma tv with her.
If you're just looking for an excuse to go out and buy a brand new tv, and 60" and less than $1500 is your criteria.. I'd hold off.
Sony S5100 BD-Player
Sony HT-XT1 Sound Base