I've reached Gran Pulse and I'm loving how open it is, It's fun watching all the creatures on screen while running through the vast plains.
Quick questions: What's the best role for each member? Also, is there a specific party I should stick with for the endgame/post game?
This is just my take, so take it as it is:
Fang = best Commando; Great as a Sentinel, great as a Ravager late game, good as a Saboteur, and okay as a Medic. Makes grinding turtles post game a breeze.
Lightning = best Ravager; She's good as a Commando, is a Medic in a pinch (bad casting speed takes her down a bit), some good Synergist spells late game making her pretty damn good as a Synergist, and can function as Saboteur. You
can make her a good Sentinel, but that requires accessories. Basically, an all rounder who can step into any role and do a good job.
Snow = best Sentinel. Good as a Commando. If you want to use Snow as something other than a Sentinel, you have to take advantage of his casting speed (he's the fastest caster by a good margin).
Vanille = best Saboteur. Not as good as Hope as a support character, but isn't as squishy to compensate. Great as a Medic and good as a Ravager. I've
heard you can exploit her as a Commando, but to me, if you have to go through the trouble of exploiting the game, it's not worth it.
Sazh = best Synergist. He's a Commando who can't launch and doesn't have most of the auto abilities; a Ravager who misses over half the move set; a Medic who can't raise; and a disappointing Saboteur and Sentinel since he's behind Snow and Fang no matter what and you can build Lightning into a better Sentinel if you want and Vanille, Hope, and Fang steal the show Saboteur wise. I found him situation based.
Hope = best Medic. Can step into any of the support roles with ease. Super squishy.
Late game, I used Lightning/Fang/Hope (gives you access to the most amount of abilities and is a rather safe party) or Fang/Lightning/Vanille. However, playing it this safe
can make the game a bit boring, so experiment a bit.