Joe:
Walked this route last year. Started on April 1st from Irun. At this time of year, I believe it is a great alternative to starting in SJPdP. The first few days you walk in and out of the coastal area towns through the valleys and on some pedestrian paths. Once you get past Beasain it becomes much more like the Frances. Rural walking through hilly farmland until you get to Zerain. Here I had a difficult time picking up the trail which wove through farms, up ravines and over fences. The path was mostly a horse trail through the hills until a decline into Zegema. A very interesting and beautiful path. Zegema provides a very steep climb up the mountain, much like the climb from SJPdP. This climb is very steep but not as long. Just before the peak you come to a tunnel, about 70 meters long through the mountain. his is followed by an old Roman road to the woods and then down the mountain to Salvatierra. The next day you walk to Vitoria/Gastiez a large city (230K) that used to be the capital. The next couple of days you walk through farmland and come to the option of SDdlC or Burgos, forget the exact spot but it is by the highway. Prior to Brinas and Haro there is a steep climb after which you are rewarded with spectacular views of the river, and old Roman bridge and the wine country of Brinas and Haro. This was the first place I encountered any other Pilgrims. The next day you reach the Frances and Santa Domingo de la Calzada. The Cathedral is worth a stop but I walked on to Granon, one of my favorite Albergues. That said, the Albergue in SDdlC is nice.
I really like this route. It is very Basque with few Pilgrims. There are plenty of Albergues. You can get a list from the Eroski site or one of the other Vasco threads. You might have to get a key at the Police Station or a bar and you will most likely have the place to yourself. That said, they all had hot water and clean beds. There are plenty of places to eat and very reasonably priced. In Zegema, I recommend you stay in the Pension versus the school which was very cold and only had a space heater.
The Vasco is a beautiful walk from the coastal cities through the valley over the mountains and into wine country before joining the Frances.
There are also alternatives to the path I took. Fatma has walked some of the detours and onto Burgos. Annie the nurse has also walked this route. I am sure they will have similar but different comments about this route.
Ultreya,
Joe