Help planning Madrid-Seville- Grenada- Valencia (with teens!)

I used to live on the coast in southern Andalucia (on a boat, actually) and remember Christmasses quite distinctly, Only two or three times was it warm enough to sit out. It could be bright and crisp (12-13 deg c) but occasionally it rained in biblical proportions. So I wouldn't get too hung up on thoughts of the coast, but stay in cities where there is enough to do if it rains or is too cold.
Are you planning on travelling by train? Are your 3 days actually 3 nights? If so, you only have two full days in each place.
Christmas Day is relatively quiet in Spain, but if you are there on New Year's Eve, there will be big celebrations into the small hours.

The high temperatures in both Valencia and Motril (on the coast one hour south of Granada) in December 2025 was in the low 50s. If driving between Granada and Valencia you could drive by some coastal beach towns between Alicante and Valencia depending on the route you take, but as Lin stated, don’t expect the temperature to be warm enough to sit out.

Are you planning on driving? Have you compared driving vs train?

I think you could make a case for omitting Sevilla and having longer stays elsewhere, but I’d want to know how the transport breaks down. Two full days per place is awfully tight…

When you say outside of museums, what kinds of things does your family enjoy?

We are thinking of taking the train between Madrid/Seville/Grenada and then driving. Does this make sense to do it this way?

Any advice on the drive between Grenada and Valencia? Also unsure what to do in Grenada on Christmas- happy to scoot out and visit somewhere else if there is more to do. I understand all of Spain will be very quiet.

Flights are cheapest in and out of Madrid for us which is why we are flying in and out of there.

I don’t know that you really have time for that—it’s five plus hours. Weather could be iffy, so you’d have to break up the trip, losing considerable time from both cities. If you have your heart set on that part of the journey, then something else will need to be reduced.