Alternatively, have the non-optimizers play clerics & druids and have the optimizers play fighters & rogues.
This doesn't help far. Druids and clerics will shine, but still the damage of optimized mundanes are HUGE.
I do the following thing in my group: I help everyone creating his char and approve/disapprove the stuff then. That means, I say to the power games stuff like "no, incantatrix is not allowed, because of ..." and they understand. Meanwhile I help the less optimizing players how to improve their character builds so they get to kind of the same power level with the other guys. This works really good because I know DnD pretty well and thus have a good sense for balance and know how to help to improve less powerful builds.
