I’ve spent several weeks in Spain (central, eastern, and southern)
A sandal with a good cushy heel and a well-centered arch goes a long way.
My wife and I have tried the Chaco Z2. We could never get used to the big toe squeeze. This past 12 months, and some of it in Spain, my wife has been using the Chaco Z1. She likes the arch. However, for long distance walking and standing, she says her Teva Tera fi2’s win hands down. She says the strapping and softness/cush is much better and they’re easier to maintain/clean.
After a year, she has now switched back to Terra Fi 2’s (now the 3’s).
I’ve also tried a couple dozen sandals and I still prefer the Teva Tera Fi 2’s for an abundance of reasons which I might have covered in other posts.
My wife does not use socks, but she will don them when backpacking. I always, and stylishly of course, wear socks with my sandals to prevent blisters, and to keep my feet from burning up in the Spanish desert.
Good luck on your sandal choice.
Disclaimer: I wish Teva paid me.