We are going to visit Maintenon, Rambouillet, Castle of St. Jean de Beauregard, Château de Breteuil, Vallee de Chevreuse, Courson Castle, Domaine de Courances, Fontainebleau, and Vaux le Vicomte. All South of Paris of course. What would be a good central spot for these to base ourselves with an easy train there from CDG and rental cars as well? Thank you!







Same question for north of Paris to visit Chantilly, Compiegne, Pierrefonds, Giverny, and Chateau de Bizy. Thanks again.

The main problem is an easy train from CDG to a hub location. You might be better hiring a car in CDG and then planning a semi- circular road trip starting in Compiegne or Chantilly and ending in Vaux le Vicomte. If you are flying long haul, you might want to consider staying close to the airport for the first night as the heavy traffic can be a challenge if you are jet lagged.
Another option could be to stay 1-2 nights in Paris and then take a train to Orly airport or one of the small towns just south of Paris to pick up a hire car for the road trip and return the car to CDG afterwards.
You have not said how many nights you plan to spend on the trip. It would be helpful to know that, what sort of pace you like and if you prefer to stay in country hotels or somewhere in small towns.

Paris is the hub for reaching the majority of the suburbs;

Thank you for your advice.