Some spanish friends who live in Marbella go here for August. We visited 2 years ago for a few days, kids love it. Great for those who don’t want to sit on a sun lounger all day or sit in a Brit bar 😀
Galicia looks great I admit. I’ve spent a few holidays on the north coast in Asturias and Cantabria and can verify there are loads of picturesque beaches (as well as stunning countryside), some of them often nearly empty even at the height of summer. However it has to be said that the climate is affected by the Atlantic, and rain can often rule out a day at the beach. You also really need to know some Spanish to get by as you won’t bump into other Brits – younger Spanish may be ok speaking a little English but many of the older generation will not.