Just an idea, since there is the reputation system, perhaps maybe adding a few custom background feats to aid in those that want to play from specific areas but don't entirely want to reply grind for the basic reputation.
Possibly give them a minor +1 or 2 on one skill and a rep penalty. E.g. Waterdeep nobility. Gives minor rep for the nobility and a rep penalty in the slums area, +1 diplomacy