When i walked Arles route i happened to be in Puenta la reina exactly for the festival of san fermin. Caught a bus from puenta la reina (or you could make a day's walk) to pamplona and stayed in a small hotel just by the park and outside of the city center. If you are there for the festival many churches and museums will be closed but besides the few minutes in the morning when folks run with the bulls, the festival is amazing with music, dance and foods from all over Spain. Of course the bulls are running to the arena for the afternoon bullfights (it is amazing how many runners do not understand why or to what the bulls are running). Unless you really want to drink late into the night, get your room outside of the very raucous middle of the city center. The festival is all around and in the park. I want to go back to pamplona to see all that was closed when i was there.
I thought the walk between Pau over the col du somport and into Spain was so beautiful that when i got to spain i got on a bus and returned to urdos to spend a few more days and walk it again.