Never been Biarritz mate so can't compare!
Beaches are amazing though. Love it there. There's a place we went to called Dune de Pilat not far from one of the beaches near Bordeaux. It's the tallest sand dune in Europe. Must admit that when we went, it's the best viewpoint I've had of a sunset and hundreds of people flock there each day (in summer, anyway) to catch a sight of how scenic the sunset can be. I'll get some pictures up later.