I will be traveling in the Loire for some time in early May. I have rented a place in Chinon. My plan was to take the train from CDG to St Pierre des Corps (near Tours) and rent a car there to drive to Chinon. I just realized we arrive on May 8, a nat'l holiday, and many/most car rental places such as Hertz are closed. I could still rent a car at CDG but I really hoped to avoid driving in that area after a long flight. I would be doing a one-way rental and needing an automatic. Any suggestions?
You just about answered your own question.
Small locations might promise you an automatic, but your best chance of actually getting one would be at an airport or a major, large city, train station.
Your only option to avoid driving around central Paris and the peripherique would be to make your way from Roissy to Orly and get a car there. The problem is that it'd be multiple changes in transportation with your junk and it'd make the entire journey quite a bit longer.
Ed's right about your best bet of getting an automatic is at an airport or a large train station. However, May 8th is the first day of a 4-day holiday weekend. Ooodles of cars will be driving out of Paris until some time in the early afternoon. You're going to get some big jams trying to get out of town unless you can get yourself down to Orly to pick up the car. You'll still have some jams leaving from there, but not as bad,...particularly after 1:00 p.m.
To avoid surface traffic, which will be light deep inside Paris but heavy on the ring road and roads leading out of the city, you need to take the RER B which connects the two airports. This is what Ed says you'll have a few switches to do from one train to another. I've never taken it, so I'll let someone familiar with the exact route tell you.
Your other choice is the Air France bus which links CDG with Orly. You just sit in the bus, doze, and let the driver hassle the traffic. This I've done.
Warning: Orly is much smaller than CDG, so the car stock is smaller. Second warning: the French rent a lot of cars to get away on these holiday weekends. There will be fewer cars available than normal. For that reason alone, on a holiday weekend I'd rent through AutoEurope, where you pre-pay in order to guarantee that the car, configured as you need, will be held for you. If for some reason it's not there, you have an 800 number--valid from France to call AutoEurope back in the States/Maine and have them work it out for you. Reps of all the rental companies have desks in AutoEurope's headquarters in Maine. Someone's on duty 24-hours a day. If you didn't have these considerations, I'd say to go with the cheapest.
Lots of great help here as well as another thread about getting to Amboise in general. Thanks for all the suggestions and ideas!