There are no games I would never play, just some I would have trouble playing so have put off attempting yet, others I never had a chance to play.
Super Mario 64 ( Never had the right console but will try it on the DS eventually)
Final Fantasy games (Like watching others play them, love the FMV's, not that fond of RPG's)
Crash Bandicoot games (will get around to them eventually)
I usually play new games now, and what time I have when I feel up to playing games gets shorter and shorter, but I still occasionally play PS1 games. Odds are I will eventually play at least one Crash Bandicoot and Final Fantasy game, not in any hurry though.