I'll probably be playing this game soon. Ive never gotten too far into it (much less beaten it), but I've been meaning to for some time now. Also since its my first time playing through I'd like to run 4 different classes instead of more than one of a certain class just so I can experience the game more (at least thats how I look at it). I'm thinking of running :

Thief - Fighter - Red Mage - Monk

It's a melee heavy group, but the red mage can cover me until I hit promotions where the thief gets black magic and the fighter gets white magic when he promotes. Does this seem manageable?