I normally booked ahead, partly because I burned out on the first week and then began to rely on correos for pack transport. I either used telephone or booking.com, and had no trouble.
My list includes a few small hotels among the casas rurales-- the only luxurious exception is the Palacio de Magdalena, which was once the Bishop of Oviedo's summer palace. If you're upmarketing at all, the Parador in Vilalba is perhaps a reasonable choice. Even if I call a place spartan or modest, it's still comfortable, and in pretty well all of them, the hosts are friendly and hospitable. Check on Gronze or on Booking.com to see if the prices fall within your range.
Casa Txurdin in San Juan Pasajes (best to call ahead on Whatsapp), Intxauspe in Markina/Xemein, Posada la Torre de la Quintana in Liendo, Posada la Mies in Noja, Posada del Angel in Guemes, Hotel Museo los Infantes or the more modest Hospedaje Maria Jesus in Santillana del Mar (which is a very touristy place– but the public albergue is nice), Posada La Solana Montañesa or the Hotel Esmeralda in Comillas, Azul Galimar in San Vicente de la Barquera (although the Luzon brings you back to another era), Hostería El Corralucu in Serdio, Posada del Rey or the Cantabrico in Llanes, Hotel Casa de Indianos Don Tomás in Nueva, Bahia in La Isla (although La Isla does not always have a restaurant in the pueblo except at lunch), Hotel Neptuno or Carlos I in Villaviciosa, Don Pedro in Aviles, for a splurge the Palacio de la Magdalena in Soto del Barco, Hotel Playa de Las Llanas in Muros de Nalon, or take a stroll to the beach at AGuilar and stay at the little Hotel Azpiazu with its very good seafood, in Soto de Luiña theHotel Casa Vieja del Sastre has both pilgrim and regular accommodation and a good restaurant, Casa Roja in Cadavedo is very comfortable and has an excellent little restaurant for guests. In Luarca, I stayed at the spartan Hotel Dabeleira and the harbourside Baltico, in Navia at the modest but comfortable Hotel Arco Navia. Tapia de Casariego has some very agreeable modest accommodation either at the Casa de Abuelo at the entrance, or Hotel Puente de los Santos or the Hotel San Antón.
In Ribadeo I have stayed at the Hotel Bouza and the Hotel Rolle, as well as the more upmarket O Cabazo, in ascending order of price. I broke my journey 19km out at the friendly Habitaciones Tentempé Peregrino in Villamartin Grande, which is much like an albergue but all private rooms. In Lourenzá I would recommend Casa Gloria, and in Mondoñedo the Hotel Montero. In Baamonde, you can stay upstairs of a automobile & truck repair facility at the modest but comfortable Hostal Ruta Esmeralda. At Regüela, south of Miraz (they will come and get you), there is the serene rural Hotel Bi-Terra with a good restaurant. Unless you break at Boimil, which is not a bad idea, it is straight on into Arzua (both the Teodora and the Casa Suiza are comfortable hotels), then the Francese autoroute.