Must have items for visiting Spain?

Hey, acouple of us are visiting spain soon. We're coming in from the north through France. We already have a plan, or most of it. What I am wondering is, what should we bring? What kind of clothing, any extras other than sun protection? We will mostly stay in north-middle Spain. San Sebastian for a few days, Bardenas Reales for a couple. We're actually hoping to find a nice spot to watch the eclipse in Bardenas area somewhere. Is very likely that we will also visit Barcelona. Sadly Madrid or Portugal are just too far for the time we have. Any tips on clothing options, or type of shoes, maybe accessories? Judging from the info we have it's mostly going to be super light stuff, with a couple of warmer items for the Pyrenees part. We are a mixed group, so specific stuff for men and women is appreciated. Also feel free to suggest tips and must visit spots in this area, from San Sebastian to Barcelona. I appreciate any help. Thanks!