One final comment about Bards/Dancers--
If you are one of those freaks who absolutely adore grinding (I'm not judging--I AM one), Bards and Dancers are a worthwhile (if short term) investment. Properly hasted and sped up, a Bard/Dancer can rack up zillions of JP per round. The Bard's healing song and the Dancer's damaging dance are both the fastest and the most likely to hit--you just have to keep your party's HP slightly low and one enemy's HP high, otherwise no JP will be gained.
TVTropes even suggests using Bard/Dancer to rack up JP for Calculator.
If you hate grinding, follow Nate's advice.
The 2 Mimes 3 Dancers strategy is pretty silly if you think about it. Although the setup makes it so you can enfeeble and slaugter an entire army without moving from your original spots, with the JP you get from trying to level Mime OR Dancer you can instead invest in a Monk with Dual Wield, a Ninja with Martial Arts, a Knight with Dual Wield, a Summoner with Draw Out, (insert your favorite combo here), and so forth.