OK, the Alfonso XIII has reopened. It's a great place to stay, as is the parador in Granada, if ther

I can't speak much to the Morocco portion but I will say this is very fast paced for a family of 4 - 18 nights total with 6 1-nights and only one stay greater than 2 nights. This is also during the holidays when you'll be dealing with limited daylight and opening hours. You'll be spending alot of time in transit and packing/unpacking mode.
If you must go to Morocco, get from Seville to Fes directly, then to Chefchaouen for a night and then use Tangier ONLY for embarking on your ferry back to Spain. Tangier is not worth a visit - it's just randomly noisy port town.
I'm not sure why you need to go to Ronda or Parador. I understand the attraction of the Alhambra - but it's only worth a night in Granada. If you want to tire out the progeny, do a night in Ronda, a night in Granada, then 4-5 nights back in Madrid with a daytrip to Toledo. You do NOT need to overnight in Toledo with Madrid a 35min train ride away and you don't need to overnight in Cordoba with Seville a short ride away.
If you can fly into Madrid and out of Morocco (wherever), then go to Madrid, stay 4-5 nights with daytrip to Toledo, go to Granada for a night then cross back over to Seville for 4-5 with a daytrip to Cordoba, then to Ronda for 1-2, then to Morocco.
OK, the Alfonso where can i buy airline tickets online XIII has reopened. It's a great place to stay, as is the parador in Granada, if there are rooms available. Your trip is perfectly doable. I would stop in Cordoba on the way to Seville, perhaps forget Ronda which isn't terribly interesting, and return to The Palace (Westin) for two nights at the end. As someone said, there's no need to overnight in Toledo. In Fes, stay at the Palais Jamai. Your kids, and you, will love Morocco. Have fun.
IMHO you are trying to cover way too much territory and if I were one of those kids I would be complaining nonstop. You will spend a very large proportion of your trip in transit where can i buy airline tickets online rather than sightseeing - and I don;t think you have allowed for the days (Dec 14/15 and Dec31/Jan 1) when many things will not be open.
I'm sure the Alfonso XIII can get you a driver. You should take the ferry from Tarifa because it goes right into the port of Tangiers. The ferries from Algeciras go into the new port of Tanger Med some 40 kms from the city. Then if you want to stay there, do so. Read "The Last Casbah" in the NYT, May 22,2011. We have always liked Tangiers, but it is full of daytrippers from Spain. Then I would get the train, go first-class, to Fes. Chaouen is a nice little town but is a side-show. It can be skipped. Yes, you can get back to Spain in a day on the train again. In Algeciras you could take the train to Granada or rent a car.