I'm working on this myself. I've already taken the trouble of taking the buggy all the way back to Junon and back again.

Now I'm grinding in the Wutai area.

The Temple of the Ancients is a great part of the game, and Aerith gets a pretty Princess Guard staff.....downside being you lose control of her afterwards, then those pretty staffs are nothin' more than Throw fodder >_<