The crowds calm down dramatically after the Feast of the Assumption, 15th August - a date that generates near-hysteria in terms of dances, firework displays, and the French delight in all crowding as many people and cars into one location as possible.
From the start of next weekend the motorways to the south coast become gridlocked, as do coastal roads from the Spanish to Italian borders. Nearly all accommodation is booked up in coastal areas but 'unfashionable' inland rural areas are more peaceful - the Ardeche and the Dordogne count as fashionable therefore are like ant heaps.
End of august / start of September - bliss.