It depends on what you want eg hotel, cottage or camping; fly/drive or drive or take train. It is a huge and diverse country with masses of differing regions, all with their own merits.
Eg go north to the coast of Normandy or Picardie - great expanses of sandy beach
Or head for the mediterranean coast / scenic cliffs round Nice. or the pine-trees and dunes round the bay of Biscay.
The coastal areas especially round the Med are very congested in August but inland there are equally fantastic riverside / lakeside places that can be less manic.
Much depends as I say on your personal taste, and whether you are catering for children.
Just remember to avoid Carcassonne in August.