We will have a week in Paris in July with our family. We are looking for a private guide who can join us for a day or two to introduce us to the best of Paris. Thanks for sharing your experience with us.
You can't do better than Arnaud Servignat who guides for Rick but also does private tours. He is fantastic.
You might try the Paris Greeters Program: http://www.parisiendunjour.fr/index.php?lang=en It's free, but they encourage donations to their non profit organization...
You might contact Lisa Burros Hutchins at yourparisexperience.com. I have utilized Lisa twice, and she is wonderful at connecting you to the best.