I think that the Core D&D rules are not very good at modelling non-high level people with influence....in some ways.
One of my primary beefs is the linkage of character wealth to character level. It makes it impossible to have a 1st lvl expert (mercant) or aristocrat who is also a millionaire. What if he inherited his money from a parent?
So that's the first thing that has to be done away with. Perhaps set it so only PCs are bound by those restrictions? It's mainly there to keep characters from amassing wealth too fast, or encountering NPCs with low levels that are loaded with powerful loot. But who's to say that every 1st lvl rich character is going to be dripping with magic weapons? In real life, who many rich people have tonnes of firearms and such? Mostly they've got nice cars, expensive furniture, paintings, big homes, etc. etc. Having an expensive gold-enameled coach isn't going to make a low lvl PC powerful in the physical sense.
Of course, this causes other problems.....like why don't PCs or powerful characters simply run amok, stealing and pillaging from these weaker characters? I guess the answer to that is, why doesn't it happen in real life? Because there are consequences. Maybe that 1st lvl aristocrat running a province is protected by not only several tough, experienced lvl 10 bodyguards, but also by law. If PCs try to off him, then he'll have the entire force of the law working against them. Given that the guard etc. have to deal with challenges on a day-to-day basis, my assumption is that they won't all be level 1. The PCs might beat one or two encounters, but what happens when another 3 squads show up? Eventually they run out of spells and resources, and will need to sleep. Sure, some characters will always want to try it....but then the DM should be there to hand out the smackdown.
And if there are lawful good or lawful neutral characters in a party, will they work with a companion who just broke the law by assaulting or killing someone? As a DM, I remind my players of this. We had an incident in one of my campaigns where a rogue physically assaulted and robbed an NPC. A lawful good character in the party actually captured him, and turned him in to the guards. He ended up going to trial and being punished for his crime. Although it pitted one character against another, role-playing wise, it made sense, and everyone had a good time as a result of it.....even the player whose character got arrested.
Even the aristocrats and such can be higher than lvl 1. XP is awarded for dealing with challenges....and those can be for doing things other than killing dragons. Characters can get them for picking locks, negotiating through some form of natural environmental condition, successfully negotiating against another character to achieve a goal, via Diplomacy, etc.
I would recommend using the Noble class from from any of various supplements...DLCS, Noble's Handbook, Rokugan D20, Swashbuckling Adventures, etc.....as well as the Courtier class. The Courtier class especially gives a socially oriented class that covers all the various people in the game who need to have roles *other* than kicking down downs and killing stuff. They're skill-oriented, with lots of points, but few hp's, and the BAB of a wizard. But great with your Sense Motive, Diplomacy, Bluff, etc. etc.
I think that DMs simply need to look beyond the core rules, and there are plenty of ideas out there.
Banshee