By all means, rent a car. We rented one on every trip for the last 20 years. We used to rent directly with companies like Avis or Hertz, but for the last several years we’ve used AutoEurope. They’re a broker and can find you the best rates. And, they’re based in Maine. If you call rather than renting on line, you’ll have a nice conversation to boot.
Your car might be from any company, but will most likely be through Europcar or Hertz. The biggest controlling factor on car size is how many people there are in your party and how much luggage you have. If you rent a smaller car, there’s a very strong chance they won’t have it and will give you a free upgrade. That can be a mixed blessing, since bigger cars get lower mileage (kilometerage?) and increase your operating costs. Also, bigger vehicles are a curse in medieval villages and modern parking garages.
Take every bit of insurance you can get. I like the peace of mind that comes from zero-deductible, full coverage. If I have to have the car returned as a burned out cinder on the back of a flatbed truck, I want it to be fully covered. Somebody will doubtless tell you that your credit card will provide this coverage. All I can say is you’d better be darned sure of the fine print. What are the restrictions? What are the limits of coverage? How long will it take for reimbursement? Will your credit be blocked up by the rental car company in the interim? Will it affect your credit score and interest rate? It doesn’t work for me. The insurance thru the car company isn’t that expensive. Buy it and be carefree.
My advice is to rent for the entire period. You’ll get a better price. And, by the time you add your intercity train tickets, you’ll be dollars ahead.
Oh, by the way, get the International Drivers Permit thru AAA. Nobody will ever ask you for it probably, but if you get stopped (unlikely) or have an accident, you’ll need it.
It sounds like a great trip. We’ve enjoyed touring that part of France in many occasions. Enjoy.