I need some ideas

I liked Valencia very much, but I'm not sure you could fill two weeks there, even with day trips, unless you go in March during Las Fallas.

I don't have another suggestion. I think you've hit the big three, and I'm not sure if there's anywhere else in Spain worthy of a two-week stay. Maybe Bilbao, because it has some good day trip potential.

Time of year?

acraven, we were thinking of late April and early May.

Lane. we can spend 2 weeks almost anywhere. We are slooooow travelers. We do a whole lot of nothing.

Malaga has a lot to see and do. We've stayed a couple of times, once for a week and a second time for ten days in November and didn't get bored, although we are slow travellers too. Malaga has lots to see and do and stroll.
https://slowtravelitalyspain.blogspot.com/2020/01/malaga-what-to-see-and-do-free-31-ideas.html

Valencia or Santiago de Compostela. Very easy to day trip around Galicia by there.

That time of year should be nice in many cities. Valencia and Malaga both seem viable, and both have airports.

Two places I like in the area around Valencia are Cuenca, which is on the AVE rail line with trips taking about 1 hour (though the express-train station, Fernando Zobel, is outside town), and Teruel, which has only local-train service taking about 2-1/2 hours. Teruel is a regional capital pretty much ignored by foreign visitors and has some Mudejar architecture. For Cuenca, you can probably snag a good fare if you buy a ticket well in advance. Prices can go pretty high for last-minute purchase.

León or Burgos

Being sloooooow travelers I highly recommend Valencia. The city and surrounding areas offer a good varied menu of opportunities and your choice of April/May is excellent. Give consideration to trips the ferry service offers to help expand your reach of activities.

To me... GIRONA, the Heart of Northern Catalonia

Just a short trip from Barcelona, one of Europe’s major air travel hubs, Girona is easy to reach while offering a completely different pace. Often considered Catalonia’s “second capital,” this city strikes a perfect balance: with around 100,000 inhabitants, it’s small enough to feel manageable and relaxed, yet large enough to host countless things to see and do.

Girona is vibrant, with a rich cultural life and traditional heritage celebrated throughout the year. One standout example is the Temps de Flors festival every May, when the city blooms with spectacular floral displays.

Strategically located in northern Catalonia, Girona sits close to both the Pyrenees mountains—featuring peaks over 10,000 feet—and the wild, cliff-strewn beaches of the Costa Brava, dotted with hidden coves. Surrounding the city, charming towns like Besalú, Pals, Figueres, Cadaqués, and Peratallada, among many others, offer a treasure trove of history, architecture, and local Catalan experiences.

Whether you’re into history, food, nature, or simply wandering cobblestone streets, Girona is a gateway to everything that makes Catalonia unique.

Here some pointers to start exploring -and planning:

https://www.girona.cat/turisme/eng/index.php
https://costabrava.org/en/
https://visitpirineus.com/en

Enjoy!

I think Valencia is an easy choice. My wife and I spent almost 3 weeks there recently and had zero problems filling our days. The Turia Park, the old city, the Ciutat de les Artes i Sciencies, the Oceanogràfic, the Jardín Botanico, the beach ... just a great city.

I agree that Valencia is a great option. We spent ten days there and could easily have stretched it into two weeks. We were there in February and weather was good.
We spend two months in Malaga each winter usually mid January to mid March and are always sad to leave. Plenty to see and do plus numerous options outside the city. Good transport hub.
Valencia’s distance to the beach is less convenient than Malaga’s so for us Malaga is the best choice.

Valencia is a great call. I also love Malaga and San Sebastian. If you like good food, then I highly recommend San Sebastian.

I hope this helps.

Thanks for all the ideas, everyone. I'll look into those sites. Right now, I'm still thinking Valencia.

What’s good is you have plenty of options. Enjoy your trip.