If you'd like to see authentic prehistoric caves instead of a re-creation then a visit to the Cuevas Tito Bustillo in Ribadesella is recommended. An added bonus is the beach and town which are lovely.
I live in Castro Urdiales. On Sunday the only grocery stores open are a Carrefour Express on Camino de Ronda and a fruteria/mini-mercado next to the La Barrera bus stop. Both are in the city center. Restaurants, bars and cafes are generally open.
Fellow coffee addict here. I check gronze.com for the next days route to see what stops are available. If it doesn't look promising the evening before I go to a bar/Cafe and get coffee to go. That way it's available first thing. If you're fussy about your coffee being hot this won't work but...
I just finished walking the 3 days from San Vicente to Santo Toribio. Gronze.com has gps tracks for this route which I found really useful. The website also has information on distances between towns and available services/accommodation.
Do you mean pack transport? If so, when I walked the CF-San Salvador in 2021 I developed tendonitis part way through. A gentleman replied to my request for pack transport saying that he was committed to covering that route. When I reached Pajares he informed me that he was no longer available...
Given those 3 choices I would take #3. There is much beautiful coastal scenery between Bilbao and Santander that you would miss with Option1. Option 2 has you walking a part of the Primitivo. Why not save the entire Primitivo for another trip.
I enjoyed extra time in Ribadesella with a side tour to the Tito Bustillo caves to see the prehistoric cave art. Santillana del Mar has Altamira (prehistoric cave museum)but it's a replica, not the original deal as in Ribadesella. Also enjoyed Ribadeo with a side trip to As Cátedras. Guernica...
There was 4 years ago when I walked the Norte. Picked it up right in front of the Bilbao airport. Much has changed in 4 years but Google might have the answer.
This site is run by Ivar at in Santiago de Compostela.
This site participates in the Amazon Affiliate program, designed to provide a means for Ivar to earn fees by linking to Amazon