Loire Valley in late September

I'd plan a minimum of three full days (four nights) in the Loire Valley, up to a week if you can find that in your overall trip. With a week-long stay, I'd suggest basing in one town east of Tours (like Amboise) and another west of Tours (like Chinon) to save driving time. With a 3-4 day stay, I'd suggest west of Tours. But, really, figure out how much time you'll have and use a good guidebook to pick the chateaux and other sights you want to see, find those on a map, and base yourself as close to as many as you can. Tours itself is worth a visit, but maybe not so great as a base because of the time it takes to drive in and out of the city. Besides the chateaux there are vineyards, Troglodyte caves, walled cities (like Angers and Loches), and one of Europe's great zoos at St-Aignan if you get chateau-ed out. A couple of chateaux a day is a good pace, and take a break now and then.

My favorites -- Chenonceaux, Blois, Amboise, Clos-Luce (in Amboise), Chambord, Loches. All west of Tours because that's what we had time for. There are many others, and many different preferences (though I've never encountered anyone who didn't put Chenonceaux high on the list), so pick your own.

Skyscanner can help you find flights. I looked for something from Tours to either Pisa or Florence and came up with nothing that made sense, so maybe your best bet is to drive back to Orly and fly from there. Generally you can return a car to a different city in the same country without a dropoff charge.

I would get a train from Paris to Tours, rent a car and base myself somewhere nearby for 3 to 5 nights.
Four full days could see you visiting up to 8 chateaux. Chenonceau and Chambord are the standouts.
Villandry, Usse and Saumur also rate for me. This is a great overall guide to the best chateaux of the Loire.
http://www.frenchmoments.eu/top-10-most-beautiful-chateaux-of-the-loire-valley/
I think a return train to Paris and flight to Pisa is your easiest option for an onward journey to Lucca.

The TGV train from Paris to Tours is wonderful. FAST and easy journey.

My friends and I took an early morning train so as to have the full day visiting a couple of wineries before heading back to Paris. I had just finished my coffee and was thinking about a second cup when the train started to slow for arrival. That fast!!

We rented a car from Hertz (I believe) that was quite close to the train station in Tours. I wish we could have stayed for a couple of days, but one day was better than none.

Seeing how you already have a car you will have to get hotel or B&B,we are staying five nights in a B&B in Vouvray which is nine km from Tours,we are taking the train from CDG to Tours and getting our car there.We booked our B&B in February for our stay in mid September.I would look at Ricks book for lodging and he has a good section on the Chateau for visiting.
Mike

Are you planning to spend any time in Paris? I ask because it's usually a bad idea to rent a car right after a long flight. The jetlag and lack of sleep make driving unsafe. If you aren't spending at least your first night in Paris, it's best to take a train to Tour as suggested and either getting the car immediately for a short drive to your lodgings or, better, then next morning.

rome2rio.com is another way to find plane and train options.

I absolutely love this forum, but I'm having trouble posting a reply. I wrote a long thank you, clicked on "Add Reply" below this box and nothing happened. If this posts, would someone please tell me how to know when my post is accepted. In m original thank-you, I tried to express how appreciate i am for all the experienced, thoughtful help you give. I read the last 2 months of posts about France, and could have spent the day here. You all are the best and we are now following all your suggestions. Thanks SO MUCH!

Reading you loud and clear. Great to be of assistance. Love to the Clintons.

I say take the TGV to Tours and stay near the train station (eg: Le Grand Hotel, Ibis,. Mercure ).

Once in Tours, take a walk to the TI from your hotel (it's very close) and get a list of excursions to chateaux. There's a company called LE QUART DE TOURS http://www.chateaux-tours.com/

They take you by minivan to a few chateaux and offer you discount pricing to get in. This, to me, cuts out the head ache of trying to drive or take the train to these destinations. Now keep in mind that it's only a transport service, don't expect a tour or your admission paid. They give you time for lunch and there's always a stop in a wine cave (no pressure to buy, but EAT the rillettes offered to you! Yum!)

Once you're back from a long day of chateau hopping, Tours is a fantastic city to recharge or relax. Go to the medieval Place Plumerau or the historic Rue Colbert for a nice dinner. There's also a charming Guinguette next to the Loire River.

I would say two days would be enough for this adventure.