Peaceable Projects Inc. is a U.S.-based non-profit group that brings the vast resources of the wide world together with the ongoing needs of the people who live, work, and travel on the Camino de Santiago pilgrim trail network in Spain.
2002 CF: 2004 from Paris: 2006 VF: 2007 CF: 2009 Aragones, Ingles, Finisterre: 2011 X 2 on CF: 2013 'Caracoles': 2014 CF and Ingles 'Caracoles":2015 Logrono-Burgos (Hospitalero San Anton): 2016 La Douay to Aosta/San Gimignano to Rome:
I prefer to have an idea of where I would like to stop each day. This year I have planned to walk an average of 20kms per day by using http://www.godesalco.com. On this website you can choose how far you want to walk each day and the website offers a printed itinerary with mileages, progressive mileage, symbols for accommodation available etc. It also offers a print out of every town and village so even if you walk further you know where the refuges are. You can also download a profile of the route you are walking.
There is no way of ensuring a bed if you plan to stay in the refuges but there are usually small hostales or fondas to stay in if the albergue is full.
I was very careful in planning what to take with me, but didn't plan an itinerary more than a day or two in advance. That way, I could easily vary the distance walked based on how I felt at the time. I had some 10km days, and some 35km days. I doubt I would have planned either in advance.
You can't do much to guarantee that you'll get a bed, but it's really not worth worrying about. You'll find somewhere to sleep, even if it's on the floor somewhere.
I've got a rough idea but only based it on having done it all before:
SJPdP - Roncesvalles
Roncesvalles - Larrasoana
Larrasoana - Cizur Minor
Cizur Minor - Puenta la Reina
Puenta la Reina - Estella
Estella - Los Arcos
Los Arcos - Logrono
Logrono - Najera
Najera - Santo Domingo
Santo Domingo - Belorado
Belorado - Atapuerca (or possibly Cardenuela Riopica)
Atapuerca - Burgos or Tarjados
Burgos - Castrojeriz
Castrojeriz - Fromista
Fromista - Carrion de los Condes
Carrion de los Condes - Terradillos (or if I'm feeling stupid Sahagun)
Terradillos - El Burgo Ranero
El Burgo Ranero - Leon
Leon - San Martin
San Martin - Astorga
Astorga - Foncebadon
Foncebadon - Ponferrada
Ponferrada - Villafranca whatsitsname
Villafranca - La Faba or O Cebriero
La Faba - Triacastela
Triacastela - Barbadelo
Barbadelo - Hospital de la Cruz
Hospital de la Cruz - Melide (or somewhere else that's less grotty!)
Melide - Pedrouza
Pedrouza - ... SANTIAGO!