Aeon Tours offers walking tours of Paris.  They offer small group, specialized tours that focus on the different neighborhoods and attractions in Paris. 

Guests can choose to get a broad overview of the city with their Paris Essentials Tour or visit the smaller, more intimate neighborhoods via their Classic Marais Tour, their  Latin Quarter Tour and their Tour of Montmartre.  If you are more interested in a specific site visit, they have a Louvre Museum Tour and a tour of the Palace at Versailles as well.  For a completey different Parisian experience, Aeon also offers a Wine Tasting in Paris.

If you are traveling as a couple or a small group, they even offer a Private Tour of Paris which might be a good fit if you are looking to avoid the standard Paris sites and want to take a more nuanced tour.