Weekend Dungeon is usually a good place for it early on. Here's an idea of the hardest-hitting things in each one so you can decide which difficulty to run:
Master - Divine ____ Mask (9999, five turns), ____ Light Carbuncle (9516+, two turns, boss -- and there are two of them)
Expert - Sea Serpent (5910, four turns, boss), Dragonette (5460, three turns, boss)
Int - lol
Novice - lol