Where is the best place to farm experience in Final Fantasy XII?
The best place to grind for experience is at Pithead Junction C in the Henne Mines. Use the switch and kill the Abysteels. Flip the switch and kill more Abysteels. Repeat as needed.
You can also chain the Dead Bones (found in Nabreus Deadlands / Overlooking Eternity) for a pretty good amount of experience.
Equipping your characters with Embroidered Tippets will ensure that you make the most use of the experience.