We are planning on a hiking portion of our trip to Spain and am contemplating Picos de Euorpa. We have some great recommendations for hiking near San Sebastien but want to inquire about the Picos. We are travelling from Bordeaux and will be moving on to the Rioja region after hiking. I know the logistics of staying in or around SS would be much easier but would be missing some incredible hikes if we do not go Picos de Europa??
I have no useful information for you other than to say that images of Picos de Europa I've seen online are absolutely stunning. They haunt my dreams.
I am leaning toward including the Picos in our upcoming trip. I’ll write a trip report about the time we spend there. I think that this is way off the Madrid/Barcelona/Seville itineraries.
Sorry I also have no first hand knowledge but will in the future be on a similar itinerary except in reverse to what you are planning.
For hiking and other outdoor activities I use the Komoot app.
As a starting point for planning you can utilize the information from hiking trip outfitters, for example On Foot Holidays has a trip in the Picos. I can personally vouch for the quality of their self guided trips having done several of them if you were looking for something like that and at the very least the accommodations they select have ranged from very good to excellent.
We traveled to the Picos 3 years ago and LOVED it. We used InnWalking for a self-guided supported week long trek. The mountains are stunningly beautiful and most people we encountered were either local or from Europe, so for us (USA) it was a refreshing break from tourism. The one hike that was crowded (but definitely worth doing) was the Cares Gorge. Arenas de Cabrales is a good base (nice small town) if you are doing hikes on your own. The Enol and Ercina lakes area has a lot of great hiking, as well as the Sotres area. Our quietest day, only sheep!, was the varied hike to Soto de Sajambre. Definitely do it!