Willie we spent three days traveling around the Loire Valley and few years ago and enjoyed it immensely.
To enjoy this area a car is essential and we drove down from Paris, dropped the car off in Bordeaux and took the train to Avignon. I would recommend that or taking the TGV to Bordeaux and perhaps paying a visit to some of the great wineries in that region before heading up the Loire valley. Some of the worlds great wineries are a short drive away.

After driving from Paris we made Tours our base and stayed at the quite comfortable and centrally located Hotel De L Univers. The old town including the cathedral, the Loire etc were within a short walking distance., ( not the mention the an impressive 200+ year old oak tree).

The are literally dozens of major chateaux in the valley and if you are not careful you might suffer “chateaux burnout” I would suggest you select a few that interest you, rather than try to see a whole lot.
If I had to see say, four they would be:
The huge and impressive Chambord the largest in France, with its adjacent stables which put on equestrian shows. Some visitors consider Chambord “cold” probably because most of the furniture has be removed ( during the Revolution? )
Cheverny which is all Chambord is not, elegant, compact and chock full of furnishing.
Villandry more famous for its incredible geometric gardens.
And yes Chenonceau that famous picture everyone sees on French travel brochures of the chateau astride the Cher. Incidentally I had one of my most enjoyable lunches in the region at one of the restaurants on Chenonceau’s grounds, L Orangarie.

I found the Eyewitness travel guide of the Loire Valley, with the 3-D illustrations of the major towns and buildings in the region really useful.

Enjoy the trip.
mike