I think the games that have the most playtime from me would be between Final Fantasy VII, Super Mario RPG: The Legend of the Seven Stars, Okami, and The Legend of Zelda: Ocarina of Time. Super Mario RPG and Ocarina of Time don't keep game time recorded, but I'm sure that I've made it passed the hundred hour mark on each, especially if you take into account the amount of times I've played through them.

As for a single file, I once had a save file from Final Fantasy VII that I played until the clock stopped keeping the time (99:99:99), and then just kept playing for Lord only knows how long after that. That was going to be my perfect file too, but one of my brothers saved over it...so I lost all that work I put into maxing out Materia, leveling up characters, breeding chocobos, and doing other sidequests and minigames.

As for longest time for playing a game non-stop, that would most definitely go to The Legend of Zelda: Ocarina of Time. I stayed up all night playing it, but then was punished for staying up too late playing a game.