It’s not too hard to get a double room with private bathroom (most if the time!) in private albergues and some hotels are available in larger towns.
Occasionally you will come across a Parador on your route and they can be a little oasis.
But...
You will find for example small hotels like San Telmo in Fromista which doesn't even have a star rating is very comfortable and offer amenities like a large courtyard and laundry facilities along with a number of first class restaurants a block...
You might try some of the top-end tours, such as those offered by Nat Geo. That's the kind of accommodation they offer, plus full support for a nice walk.
Encouragement to go outside the comfort zone - lots of us who are in our 60s and 70s stay...
I forgot to mention Paradors. I'll let them introduce themselves and others, who have stayed in one or more, can add their opinions.
https://paradores.es/en/
They have a club (free membership) that will give you some perks...
I'm not sure how hotels are rated worldwide but Spain rates by amenities supplied. It isn't by perceived quality. You may find you like a 3 star hotel just fine. The webpage below covers what you can can expect for each rating...
yep. just use booking and you're set. sometimes they aren't exactly 4 or 5 star hotels, but, for example, places that are awesome and offer the creature comforts you would expect for the price. Estella, Castrojeriz, Frómista, Carrión de los...
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