Hey
In my FR campaign, I make use of all the NPC classes.
Specifically, adepts form the lower echelons of the churchs, while clerics fill the roles of missionaries, defenders, upper hierarchy, and "fund" gathering. When the PCs roll into town, the common church of whatever deity is led by a mid-level cleric who may or may not have a lower level cleric apprentice in tow, and several adepts of low to mid level. A rare high level adept is mixed in to represent an older clergy member. The bulk of the healing is performed by these guys. Adepts also fill the traditional roles of midwives, witches in the woods, humanoid tribe witchdoctors, demon worshipping cultists, and anyone else I feel should be able to cast divine spells without necessarily having weapon or armor training, or the ability to channel energy. Oh, for the record, my adepts have spell lists based on the domains of their deity ie their first level spells are the first level spells from each domain of their diety, with whatever filler is necessary. They are also proficient with the same weapons as wizards, not simple weapon proficiency, and have no armor pros.
Warriors are fairly common, as I maintain that the only people who become Fighters are those who have trained extensively (and I mean extensively) in a military, with a mercenary company, or at a weapon academy. Thus the great majority of fighter types are, in fact, warriors or warrior/fighters. The town militia, city guard, standing army/mercenary grunt, street tough, town bully, sheriff, woodsman, besieged farmer on the frontier, castle guardsman, bodyguard, and anyone else with lesser weapons training most likely has a few levels of warrior.
Aristocrat is a fine class, though I have removed the weapon and armor proficiencies. As someone already mentioned, not every courtier should be able to wear havy armor and wield a greatsword. Instead, they have simple, rapier or longsword (depending on geographic location), and pistol or longbow (again, geographic location). They also get simple armor and shields. I removed some skills, mainly to stop an aristocrat from stepping too much on the rogue's toes, and added the 1st level abilities of the Courtier class from theRokugan campaign setting, split over the first 5 levels.
Expert and Commoner are untouched.
I do not stat every Joe Bob and Gary of my campaign world, however, my PCs tend to conscript locals in their fights. They also like hearing the dice rolling behind the DM screen when the ask a sage what he knows about what, instead of me decided what to tell them. Frankly, I concur. Because of this, the ability to stat up NPCs which are obviously weaker than PCs is a boon to me.
Thanks
-Matt