Dog on the beach

Good evening, my wife and I would like to spend summer holiday next year in France with our dogs, a sheltie and a bichon frise.

We did check on "30 million d'amis" website and got the list of the beaches where dog are allowed.

But they are allowed just on lead or before/after a certain time.

Any experience or advice on where we should go, which are the best beaches for let dogs play free... anything really might be helpful.

The area we would like to visit are south-west: Bordeaux/Biarritz.

Thank you in advance,