12 day Spain itinerary

Toledo can only be accessed from Madrid (and you have to go through Madrid from Toledo to go anywhere else). I've done a lot of the car vs. train analysis for southern Spain, and what we decided for our recent trip was to only use a car between Sevilla and Granada. Trains are faster, easier and probably cheaper. (I say probably because with four people, it might make more sense financially to rent a car, but still, the train is so easy) I don't know what you mean when you say Cordoba as a stopover. Like for lunch or overnight? It's a great city, we stayed two nights. Barcelona is amazing, and I think you will find that 3 nights is barely half of what you need to really experience it. In my opinion, Madrid is lovely, nice, etc., but doesn't hold a candle to the other places on your list. If it were me with that number of days, I wouldn't stay in Madrid at all. Give one more night to Ronda and two to Barcelona.

Maybe do the two nights in Toledo before going to Madrid. It seems like too much flying into Madrid and then taking a train to Toledo and then going right back to Madrid next day. Or just do Toledo as a day trip from Madrid. Renting the car in Seville and flying to Barcelona from Granada makes sense.

I would stay in Cordoba overnight on the way from Madrid.

We flew from Seattle to Madrid and took the train to Toledo. Wonderful 1st town!

We just used trains throughout our 3-week trip and an occasional bus. Easy transportation! We didn’t go to Barcelona.

Toledo 2 nights (add a night to avoid checking out of a hotel the first morning of jet lag!). You could take a morning train to Madrid on the 2nd day).
Madrid 2 nights. (Royal Palace & Prada Museum/Retiro Park?) Enjoy the tapas nightlife and main squares in the evening!
Cordoba as stopover
Seville 3 nights
Ronda 1 night
Granada 2 nights
Barcelona 3 nights

For your time, this will give you a nice overview of these towns!

If at all possible, I recommend spending 1 or 2 nights in Cordoba. The Mezquita is amazing, but there is a lot more to Cordoba than just the Mezquita. We loved the gardens of the Alcazar, Palacio de Vianas (small palace with 12 patios), the Juderia, and the Roman Bridge. The bridge is lit up at night with gorgeous views of the Mezquita, also lit up. We stayed 2 nights and could have used a 3rd.

If you really want to see Ronda, you should. However, I would like to add that when I was doing my research for our trip, I got the impression Ronda is considered a "lesser" site. Cordoba is an amazing historical city, with history, architecture and influences from Christianity, Muslim and Jewish religions.

Madrid could be the absolute best city for European paintings at the Prado, the Thyssen and the Reina Sofia, if that's a high priority. If not, Madrid is the least interesting of the cities on your itinerary. That's not to say it's not a good destination, just that all the others are more remarkable.

I like Toledo very much, but you're trying to do too much unless you drop Madrid. Then spend 2N in Toledo, then Cordoba (1-2N). While Cordoba can be a day visit from Madrid, going from Toledo adds at least another hour to the journey.

If you rent a car, you could enjoy the scenic driving through the hills with an overnight in Ronda. You'd want to rent the car the evening before in Sevilla to get an early start. If you do that, you may even want to spend 2N in Ronda. Consider whether you'll be comfortable with 4 adults in a relatively small car and hours of scenic driving. Even fairly large cars don't have much luggage space. Without a car, skip Ronda.

2N in Granada gives you just enough time to see the Alhambra, the cathedral and maybe the Albaicin - depending on when you arrive and when you leave. And yes, fly from Granada to Barcelona

You have only 2 days in Barcelona, not nearly enough.

I think we will do Toledo as a day trip from Madrid and drive through hill towns without staying overnight to gain more time for Barcelona. It would then look like:
Arrive Madrid late afternoon 5/19
Madrid 4 nights to allow for Toledo day trip (should I take a night away here?)
Train to Seville with stop on Cordoba to see Mezquita
Seville 3 nights
Rent car to drive through hill towns before arriving late in Granada
Granada 2 nights
Barcelona 4 nights

Thoughts?