This is how I'm planning to go;

Vaan - White Mage/Green Mage/Thieving whilst that's not going on
Baltheir - Physical attacker/Techs
Fran - Physical Attacker/Secondary mage
Penelo - Heavy gunner (Best armor and firearms I can get for her)
Basch - Black Mage/Time Mage

Ashe gets to fill any holes I end up with. Likely technicks and some magick.