My wife and daughter want to do a day trip to see 2-3 ch teaux during a June trip to Paris. They do

My wife and daughter want to do a day trip to see 2-3 ch teaux during a June trip to Paris. They do not plan to have car, so a commercial bus-based tour seems the best. We are seeking recommendations--which tour company? which ch teaux? which day of the week? etc?
There is absolutely no need to take a bus to the Loire Valley to be able to enjoy some of the finest ch teaux in France. Loco s list includes map of los angeles area some of the most memorable and historically and architecturally significant structures in the country.
map of los angeles area However, to answer your question, if I were to attempt what you are purposing, I should take the early morning TGV from Montparnasse to Tours Centre (not St Pierre des Corps), walk across the street from the station to the Office de Tourisme and take one of the many mini bus tours. The train is only 1 hour from Paris, not 3 hours as is the bus, and you will have more options in selecting the itinerary which interest you.
Thank you, loco. We (they) have been to Versailles, Vincennes, and Sceax. We will take some day trips by train, but they are looking for tours that go to some of the places that are not easy to reach by train. I plan to go with my wife to Chantilly.