My best advice, consider these my opinion and use them to whatever extent makes sense to you:
There is so much to see in Spain, it works really well to pick north or south for a two week vacation. North will be cold in March, wear warm clothes. South won't be as cold.
Tangier is to Morocco what Tijuana or Ciudad Juarez are to Mexico. You can't visit them and come close to experiencing the country. I really liked Tarifa and Gibraltar, I think they're both worth a visit. I didn't ferry across to Tangier because I want to visit Fez, Marrakesh and Casablanca when I visit Morocco rather than a gritty industrial port city.
Seville has much more to see than Cordoba. The Alcazar, Cathedral and the old quarter in Sevilla are all close together and all outstanding sights to visit. Cordoba has a smaller quarter and the Mesquita. It's definitely worth seeing (the Mesquita is unique and amazing) but with limited time may best be seen as a roughly four hour stop between Madrid and Sevilla by hopping off one train and on to a later one.
Toledo is a great town, you won't regret two nights there. The food, atmosphere, sights, lodging and food prices - everything - are head and shoulders nicer than Madrid. You will be there in March so Madrid's parks won't matter. The only sight that is a must see in Madrid IMO is El Prado, it really does live up to its reputation. It's a short walk from El Prado to Atocha station where you can catch a train to either Toledo or Cordoba/Sevilla.
I really liked Ronda as a stop. It seems to offer more than most hill towns. The white towns don't really dot the countryside around Ronda, it's not like Tuscany. I loved the prehistory passage tombs in Antequerra. I was glad I had a car to make that a stop between Granada and Ronda.
Training from Toledo to Granada isn't the best. Maybe it's not the case anymore but for awhile it included a bus connection for part of the trip. I'd at least compare just taking a bus. Buses are nice, cheap and never full in Spain. If you don't have a car, check out the day trips offered at bus stations.
To get back to Madrid from either Seville or Cordoba a train will work well. That stretch and Madrid to Barcelona are the best train routes in the country (plus the short spur Madrid to Toledo). After those, train service goes downhill pretty fast.
Worth changing your plans for is the Valencia fire festival, las Fallas. It's the 15th to 19th of March in 2019. If it were me, I'd adjust plans to experience it in person.