10 to 11 days southern spain

ViaMichelin gives two proposed routes. Both run near the coast to Valencia. The first then swings inland well to the west through a bunch of towns I've never heard of until it reaches Jaen in northern Andalusia. I don't know how scenic that route would be between Valencia and the area just north of Jaen. The other route option leaves the coast at Valencia but remains much closer to it and passes through or near some places I have heard of but never visited, so I can't comment on which route might be preferable. I see that both routes are estimated to take close to 9 hours, and that excludes stopping, navigational errors, traffic tie-ups, etc. There's an 8:35 train departure from Barcelona that would get you to Granada in just less than 6-1/2 hours--and you could eat along the way. I wouldn't drive unless I had specific plans for sightseeing stops.

What time of year is your trip? I think Sitges could be pretty dead midweek in the winter. Small commercial art galleries (by which I mean places you buy things rather than art museums) may not be open every day of the week even in high season, and they may not keep regular hours even on their purported opening days in the off-season.

How much time can you allow for this drive? How many nights do you plan to spend along the way? Barcelona, Seville and Granada alone will fill your allotment of days by the time you include transportation between them. (Granada's a bit smaller, so I'd throw more days to Barcelona and Seville.) What city do fly into? What city do you depart from?

I think your husband would like the Fundacion Rodriguez-Acosta in Granada. It's a private collection in a very nice setting (partly outdoors) and blessedly uncrowded. Entry is by tour, so you need to check the website ahead of time to see when tours are offered. I was very lucky to just show up and find an English tour would be starting very soon. There's some additional info about the foundation here: https://www.lovegranada.com/museums/rodriguez-acosta/. Both websites indicate the foundation's museum/gallery is currently closed without (as far as I can see) saying when it will reopen. The total closure doesn't seem to be a regular seasonal thing.

The Picasso Museum in Barcelona is a zoo. The Miro museum on Montjuic is a much more pleasant environment for viewing art, though it gets its share of visitors. The MNAC is a large art museum, but it has at least two unusual collections: frescoes rescued from very old churches in the Pyrenees and decorative art from the modernista period.

If you are going through Madrid the Sorolla museum is wonderful. In the opposite direction but not far from Barcelona the Dali Museum and his house in Cadiques are both fun and charming.