Like Lane, I would also consider moving to Galicia.
Five nights is about right for Santiago, and then you have SO many other small cities to choose from....with a car,, you could combine with Oviedo/Gijon/Arriondas, etc etc, in Asturias and then move on to Galicia.
There are cheap flights from Santiago to Lanzarote and we had a great trip in (I think, 2024) of about three weeks split between Santiago, Pontevedra, Isla de la Toja, and then flying to Lanzarote.
If you are an architecture aficionado, Lanzarote might be your place, not to mention the glorious wine areas and the Timanfaya Park.....who knew there were camels in Spain (??)....(not me, until we saw them in Timanfaya). Small island, very varied food stemming from the variety of immigrants who lived there now, with their different heritages...such an astounding surprising to us......extraordinarily welcoming people. The island is NOT all resorts catering to visitors from the UK. Look at towns like Haria, Famara and Teguise, among many others. Many small local inns with great food on site in the evenings.
I go in March to the South, near Vejer and combine that with one other city..Cordoba (5 nights a few years ago); Jerez (same); Sevill (a week last year) , Cadiz, etc etc. But car should be rented for the area near Vejer.
Might be a good tine to spend a few weeks on Mallorca as well if that is of interest.
We hope to spend a few weeks next spring or fall, again on La Toja/O"Grove and, as I mentioned I will be near Vejer in March.
Do you now well the area around Pedraza, Sepulveda, Roa, Campaspero, Segovia????? Especially if you are a food lover........
Or the UNESCO site of Las Medulas, and parts of Leon, including the Gaudi palace in Astorga, easy to combine with Asturias or Galicia if you rent a car????