@therovingreader cool that you have plans for spain. I didn't visit North of the Spain. But in South Spain, I can surely help you out with some cool recommendations. If you are visiting Ronda, do go for Caminito del Rey, you can buy tickets in advance or at the North Gate itself. Try to avoid weekends if you don't have tickets in advance as its usually more crowded and there are limited number of tickets per day.
Next you can plan to visit Seville and can cover all places in a day. Places - Plaza de Espana - visit in morning when its less sunny as its an open area, Real Alcazar & Seville Cathedral - Crowded places so can visit around lunch time and Metropol Parasol - A beautiful wooden structure in the center of the city. If you are going in October, don't miss on the bullfights (we couldn't see those) and at last if you wish to watch some flamenco dance.
Let me know how much time can you spare out, I can recommend very good places in Cordoba and Granada if you wish to cover these places.