If taking up Jo001's suggestion of Quiberon, you might also consider the Golfe du Morbihan - a number of wilding spots in the POIs. If you end up going further south, SSW of Rochefort, you have Brouage, which is worth a visit. Otherwise, east of La Rochelle, you have Aigrefeuille d'Aunis and the Lac de Frace. SSE of Ruffec, you have Verteuil-sur-Charente. East of Oradour-sur-Glane is the Lac de Vassivière. North of Bourges, on the D940, you have Aubigny-sur-Nère, which is very proud of its Scottish connections. If you're up to visiting one of the Loire châteaux, Chenonceau is one of my favourites. Between Rennes and Dinan you have Hédé-Bazouges and Tinténiac on the Canal d'Ille et Rance, and if heading for Saint-Malo, Saint-Suliac might be worth a visit if the legs are up to it!