Are we crazy to visit the Loire Valley in late June and the Dordogne in early July without accommodation reservations? My husband and I will be there with our 18 year old son. We have reservations for our first couple of nights in France, but some of the most fun we've had has been just finding a guesthouse or B&B on the fly. We usually travel off season, though.
Assuming you have a car, your should be OK. Look for the Logis de France brand.
With a car, as Doug says, and a flexible attitude. The TI can find you a room in a pinch, but they might try to send you to a luxury Chambre d'Hote and they do charge a fee. I'd at least call ahead the morning of.
As Doug said, Logis de France chain of independently owned hotels. You can pick up the book of hotels at your first stop. Also the Etap chain is inexpensive and everywhere. Gites de France is an association of private rentals that includes bed and breakfast places. If you have a computer with you, to search ahead day-by-day, it will be easier.
As others have said, it depends on how flexible you are. And by that, I mean - are you willing to pay for two rooms because a triple isn't available? Or take a really expensive place because the lower-cost places aren't available? Or driving far away from the city center? You will probably be okay, because school vacations will have just started in the first week of July. But it won't be as easy as traveling off-season.
Thank you all. Since we often prefer to stay out of the main tourist areas, I think we'll be fine.