Taking two weeks is comfortable and provides a pleasant experience for most riders
Rest days ? - feedback seems to indicate that most people that plan (and take) rest days regret the decision - finding it harder to get started again after a day, or more, off the bike - preferring to keep the legs moving. The compromise that we used on our French trip was to schedule some half/shorter days to take in side-trips. (They were usually wine-related . . . touring a Champagne house, tasting at Nuits St Georges etc.)
