We've done France (and Northern Spain) both exceptional holidays.
In France, we had the first and last night booked to accomodate our ferry bookings (Roscoff). Then armed with the Yellow Michelin Local Maps we just picked a route each morning that looked good. We then looked for accomodation around lunchtime and spent the afternoon exploring the local area (or sat drinking wine all afternoon!)
This used to be my technique but I travel with a laptop nowadays and book a day ahead. I'm aiming for Croatia this year via a liesurely drive through France and Italy.