Sagalouts - a guide book has its good points you know, even if it doesn't hold all the options...!
I was in Aviles about three weeks' ago. Many were not wanting to do the full 39k to Soto. Some were heading for the hostel in San Esteban ~23k, others had found some accommodation in the fishing village of Cudillero ~30k. Both are slightly off the Way. For San Esteban: after Soto del Barco (at 20k) you go over the long river bridge and take the first turning right and it's 2k directly further on. For Cudillero, when you get to the main road at El Pito just go straight along it (rather than turning left off it) for about 2k. I heard it's pretty. Waymarking on the last 5k to Soto is poor and at times counter intuitive, especially around the road bridges. Hopefully there'll still be some pebbles and arrows in the sand pointing the way...
I didn't hear of any cheap/pilgrim accommodation between Soto and Cadavedo. There is a camping complex a few k after Cadavedo and you'll see more info about this in the Cadavedo albergue if it is full. I went straight through Luarca/Almuna going another 15k to Pinera, where you have to get the key 1km before the albergue. You go back for the evening meal in the house,which was one of the most enjoyable experiences of this camino. La Caridad is another 16k further on. The albergue is smallish but fresh and new. I just stopped for coffee. Look for a panaderia on the high street that does about 8 types of excellent empanada (though I only sampled a couple). We went straight through to Tapia, about another 10k. If you take this coastal option, when you get about 4k out of La Caridad you have the option of taking the coastal path instead of the camino, the GR E.9. This is fine if you have time - occasionally a bit circuitous, but very rewarding.
cheers, tom