This is one of those decisions (socks, footwear, which backpack and how large being others) where the opinions will be all over the map. The weather will change dramatically from start to finish. I started in September in short sleeves, shorts, and a sunhat. By Galicia, I was wearing a toque and mitts, and an insulated jacket, in the mornings, and by Santiago I had full rain gear on. I took a sleeping bag, in 2014, and only used it a few times. Last year, I took only my silk liner (but I was travelling in July and August) and I found that blankets were available in almost every albergue - once I had to ask for one because they were put away in a cupboard. This year I am planning on taking the Costco throw, which I will sew or button along the bottom to create a pocket, and my silk liner.