Alright, I know I was so for playing the game "naturally" a while ago, but now I'm simply forced to bug-level.
The reason is simple: the Mysidia Tower is, as I recall, infested with status ailment-loving monsters, so I'll have to work up my Esuna spell in order to actually survive (it's no fun getting this Toad spell on my party without being able to cure it ).
Also, there're these Gigas guys, so I'd like some worked up spells for them as well.
So therefore I'm right now boosting my spells, and right now this is what I'm aiming for:
Esuna 7 (earlier mentioned reasons)
Fire 10 (for the Ice Gigas)
Ice 10 (for the Fire Gigas)
Poison 10 (for the Thunder Gigas)
This is all I'll need as far as I know, but would you recommend anything else?