Nothing hardcore about N Spain
in July / August. Done it the last 2 years. Main problem will be lots of motoring in light NE'sterlies though there are numerous marinas
is (by European standards) cheap
. Best charter
option, AFAIK, is Hendaye in France
then visit Zumaia, San Sebastian, Mutriku, Bermeo, Bilbao, Santander.
Asturias to Galicia (Gijon to Coruna) is perhaps a better coast (definitely cheaper and better food) but harder to access and light on charters.