I'd say the Potes to San Glorio road rivals any pass I've done anywhere, was just a pity I did it descending from San Glorio not ascending from Potes.
Or go further west and ride the deserted roads of Asturias. Even better than the Picos. The roads around Cangas de Narcea and Somiedo are stunning . The coastal villages /towns such as Luarca and Cudillero are also beautiful as is Tapia. Can't go wrong really ....