I'm going to add to the options and suggest the south Vendee. Easy to get to, great weather. Get a gite with a pool and visit the water park, Indian forest adventure park, the Puy du Fou as well as the beaches and La Rochelle.
Great, thank you everyone. I'm just off to explore these options. Kids would enjoy shopping, tennis, swimming, games, bowling, eating out, hiring bikes, kayaking, theme parks etc. We like historic towns, countryside, walking, nature, gardens, shops, French markets, etc