Quote Originally Posted by Cheiromancer View Post
The easiest way of slowing down a high tier character is to require multi-classing.

For instance, make a wizard take one off-level by level 10, and two more by level 20. She'll get 9th level spells at level 20 as a capstone, so that is fine. The off-levels could even be prestige classes that sacrifice caster level.

It doesn't change the relative rankings much: high level wizards are still more effective than high level rogues, but it masks the differences.
A little similar to, but probably more elegant than my prior proposed fix (having all full casting classes be prestige classes which could only be entered at a level that meant you'd get level 9 spells at level 20, i.e. level 3 for Sorcerors, or level 4 for Wizards, Druids and Clerics; you could either have some arbitrary skill level requirement in Knowledge (whatever) and/or Concentration to enable this, or simply make it a straight-up class level requirement).