2 Options After Sevilla

By staying in the south you’d save some travel time and have more time to visit places. My vote is for renting a car and visiting some of the smaller towns in the south.

By far, my top pick would be: rent a car and travel to some white towns, but not as far as Malaga.

This is not based on the current political situation in Barcelona, which has already calmed down quite a bit. But rather based on logistics, it's simply impractical to train all the way up from Sevilla to Barcelona, a 5+ hr train ride just to spend an inadequate 3 days (2 nights?) in Barcelona.

With 3 days, you are better off staying around Sevilla, where there are a plethora of fine places to see with a car: White Hill Towns, Cadiz, Jerez, Doñana National Park, El Rocío (Spanish Cowboy town), Cordoba, even a jaunt up to the historic Extremadura region.

Can you suggest an itinerary/route from Sevilla for the 3 days in the south and where to stay overnight? We have to end up in Madrid on the 4th day.

Will you already have seen Cordoba?

I agree with Carlos. Stay in Andalusia. Spend 2 days in Seville. 1 day in Cordoba. From Cordoba, train to Madrid on day 4 to head home. You won't have much time to do much in 3 days.

Stay overnight in Ronda. I prefer Granada to Malaga. We flew out of Granada because we've been to Madrid a few times.

How much time are you spending in Sevilla and what's on the agenda? Anything before Sevilla?

We already have plans for 3 days in Madrid (arriving there), 1 day Cordoba, 1 day Granada, 3 days Sevilla. Originally going to Barcelona for 3 days and last night back in Madrid and fly out the next morning, So I'd like suggestions in the south for 3 additional days after Sevilla and before our last night in Madrid. As originally posted, thinking of renting a car to see white towns, etc. to get to places not convenient by train and to see a bit of the countryside.

When you write "3 days", "1 day", etc., do you mean 3 nights, 1 night, etc.? 3 nights is just 2 full days and a few hours. One night is less than a full day, and I think that's too short for Granada. It wouldn't allow for much more than the Alhambra, and even that might be rushed, depending on how early you arrive in and depart from the city. So I'd recommend adding one of your 3 formerly-Barcelona nights to Granada. I think Cordoba and Seville could each use an additional night, but plenty of people would opt to see Ronda and perhaps a couple of the white villages during that period instead.

I've only traveled via train and bus in Europe, so I don't know what to suggest to a driver in terms of a good base for Ronda/Arcos/Grazalema/Zahara. Ronda's the largest and has the most traditional sights, but that may not matter.

Yes when I say "days" that actually mean "nights"! I'd like to visit places other than the ones I mentioned already, I need to move around a bit with my family, they don't like to stay in one place for too long (restless young adults with us).

I don't think you are spending enough time in some of your current destinations. But if they are set and you have three extra nights and must see new places before returning to Madrid, then it would be worth hiring a car from Sevilla. You could do a couple of nights driving through a white town or two (Ronda is the posterboy, Grazalema perhaps the most picturesque), and then visit Antequera which is well-worth a stop. You'll need to end somewhere that has a branch of your hire car firm and is on the high-speed rail route to Madrid - that's more likely to be Malaga than many alternatives. Or you could do a loop that returns to Sevilla or Cordoba. An alternative would be to go from Seville to Cadiz by rail, spend a night there, then drive/use the coach routes east to Malaga, stopping another night in Ronda and a final night in Malaga.

All the is rather busy - at least for me - but possible if you want to keep on the move.

Oh, that's a lot of moving around and I would have spent at least three nights in both Cordoba and Granada, but mileage varies as they say.
Cadiz could be great--I'd worry less about it feeling shuttered in winter. You can visit Jerez, drive along the coast.
That or Ronda would be my choice--Ronda especially if your group likes hiking (for Antequera, Grazalema).

Perhaps after you see how much time it will take to get from place to place (door-to-door), you will see that you are not spending enough time in some places.

Going from Madrid to Sevilla, our group stayed in the following places as well as Granada:

Toledo (1 night): Hotel Eurico www.hoteleurico.com

Ronda (1 night): Hotel Molino del Arco Partido de los Frontones www.hotelmolinodelarco.com
This is located in the countryside away from the city.

Arcos de la Frontera (2 nights): Hotel El Convento www.hotelelconvento.es
&
Hotel La Casa Grande Maldonado www.lacasagrande.net

Thank you for all the replies. Think I'm leaning towards Cadiz, then white towns/Ronda and up to Toledo and into Madrid. The hotel links are great too, thank you!