I haven't thought about it actually.

If I'm just going to do a rough guess...

Vaan - Shikari and Monk to take advantage of his high strength stat and it seems fitting for him.
Penelo - White and Black Mage which is usually how I roll with her in the regular game. Have to take advantage of her high Magic stat.
Balthier - Machinist and Uhlan sounds like a great mix of power and range.
Fran - Archer and Red Battlemage gives her a nice mix of magic and weapons. Again, not far from my usual setup
Ashe - Time BattleMage and Samurai cause hot damn
Basch - Knight and Foe Breaker cause it fits and one of them is my Sign.