The last conjurer I played had Illusion and Enchantment as banned schools. Sure, it hurt to lose basically all Will save based spells, but I love, love, love, LOVE necromancy to death, and couldn't really justify ditching any other schools. In hindsight, I didn't have a whole lot of Transmutation spells (when making the character, I forgot Teleport was Conjuration, now), so I probably could have ditched that school. Though now that I think more about it, Fly saved our butts more than once, so I guess I couldn't have ditched it. <shrug>