Remember the NPC classes introduced in 3e, the Warrior, Adept, Expert, Commoner and Aristocrat? The pretty much sucked compared to the PC classes, with the Commoner being far inferior to any other class. Except maybe the Sorcerer. I hate those guys. Anyway, the Warrior and Adept are particularly interesting to me, as they are basically recongizable as cut down versions of standard D&D classes.
So here's my idea, integrate something like the Warrior and the Adept as the backbone of the class system. Then implement more robust classes as add-ons to the baseline. Like this:
Imagine this as a two page spread in a rulebook. The lines in black are the NPC class information, with the rectangle being the spot you'd insert some artwork of a typical Warrior or Hedge Wizard or whatever. The red, purple and green columns are the buffer PC/important NPC variants, which all build off the stuff in the black columns. So if the black text said "A Warrior is someone who fights, here's his XP chart, hit dice, etc..." then the red text would say "A Fighter is a Warrior with the following special powers" or something like that. The illo box on the lefthand page would feature three characters, typical members of each of the three subclasses. (Note that in the actual rulebook the text wouldn't be different colors. I'm just trying to ruin your eyes this afternoon.)
What do you think of this approach?