I'm considering the Basque region tour for 2012. For prior to or potentially making the trip on my own, how easy is it to arrange a day trip (especially the day-long hike the tour does) using one of the French towns as a base? From the guide book, the distances in the area seem similar to those around Nice?
I don't know details about the specific tour, but if you are going on your own, and have a car, it is pretty much easier to get anywhere in the hinterland within a couple hours from Biarritz.
You can look under Tours on this website. The RS tour of Basque country starts in Bayonne, France, and ends in Bilbao, Spain. The town of St. Jean-Pied-de-Port (in France) is "a traditional starting point for hiking" the pilgrimage trail. You could study up and fashion your own day trip on the trail, or Google that town and see if there are daytrips available. San Sebastian and Guernica are included in the RS tour