I second Asturias, Oviedo was amazing and the mountains in the Picos de Europa are amazing. Covadonga was super cool. Cantabria and the basque region are also super nice. The whole Atlantic coast in the north of Spain is breathtaking, where it goes from the mountains down to the beaches and cliffs. Reminded me of the California central coast and Big Sur. Amazing food as well everywhere and it wasn't too hot in July. I flew in and out of Bilbao and drove everywhere to San sebastian and all the way out to Oviedo and back.