Southern Spain Trip Help

If that fills all the time available, I think that is a good itinerary.
Two nights in each place gives you a full day, which I always prefer.
All do-able by train, but you may need to go back through Madrid to get to Valencia.
You could do Valencia first, then Cordoba.

While you can get by with those time allocations, there is enough to enjoy in Granada for a longer visit, I think. I spent well over half a day at the Alhambra alone, and I enjoyed walking around the city and seeing the other (admittedly secondary) sights covered by the Dobla de Oro ticket. San Juan de Dios has an over-the-top interior. It's really worth seeing even if you've seen quite a lot of European churches.

I'd opt for two nights in Cordoba so there's time to see more of the city, including some of the patios.

The Manises neighborhood out near the Valencia airport has a history of ceramic production. There's a small museum there. Keep it in mind if you have extra time in Malaga << this should be "Valencia">>.

The fastest way to get from Granada to Valencia by rail involves a change of train in Madrid. A bus will not be faster; it is a long slog either way. The cost of the train ticket can be a lot lower if you commit to a specific date and time in advance.

The wildcard is the amount of time you spend visiting each place and you won’t know that until you’re there. Visit your top priority sites first in case you run out of time for anything remaining.

I would also spend 2 nights in Cordoba. Try to visit Palacio de Viana with its 12 pretty patios. Walk across the Roman Bridge at night. Take your time exploring Juderia. Cordoba is so pretty.

Since your flight is direct to Madrid, go ahead and immediately take the train to Cordoba. Then spend two nights there. I will be doing the same in February, except I have three flights to reach Madrid. (I took three flights to reach Malaga last February & immediately took the train to Cordoba, so it’s doable.)

I did just that last year. And if you buy an IRYO train ticket in Infinita class, you can take an earlier, or later train, if you run into any delay at the airport. There's no fee to change the train time.

If you've been to Madrid before- you may want to reconsider using those nights elsewhere.

Take the train from Madrid to Cordoba. spend 2-3 nights in Cordoba. Mezquita will be a couple of hours. Don't forget Siesta time where many places are closed from 12-3.

I don't think Malaga is that great. Maybe substitute Seville instead? Alcazar is amazing.

Granada is great. 2-3 nights.

I have not been to Valencia, but your to-do list there sounds great.

I found the Renfe system very easy to use. I wouldn't want to be driving in some of these places-- parking, pedestrian malls, cars not even allowed in some areas, etc.