I usually don't ever replay games, so I only beat it once.
But I started a new game and completed about... one third of the game again, but then I didn't have enough time and motivation to do everything again.
Basically, I just wanted to watch the scenes with Auron again after playing FFX-2 ^^" But when I got Auron back in my party, it became a bit boring. (Because then I'd achieved everything I wanted in my second playthrough. ^^")