I actualy played the submarine one quite alot in FFVII, i thought it was pretty fun. The Gold Saucer by itself has most games beat.

I never really got into Triple Triad but Tetra Master I spent a crazy amount of time on in FFIX. My vote would probably go to that as my favorite distraction.

Blitz Ball was really cool too, I guess with their scope, it's up to that and tetra master for me.