The tour doesn't give you much time at any location. Barcelona and Seville are extremely shortchanged, I think, given how many top sights they have:
Barcelona: 2 nights
Madrid: 3 nights (including a day trip to Toledo)
Granada: 2 nights
Ronda: 1 night
Sevilla: 2 nights
My first priority would be to add time to Barcelona and Sevilla. Then I'd add Cordoba for at least on night. If you are nuts for art museums, you'll probably need an extra day in Madrid--or you might want to spend a day in nearby Segovia.
If you still have a bit of extra time, two good options are Zaragoza (on the fast rail line between Madrid and Barcelona) and Girona, an historic city north of Barcelona.
There are many, many other options. I've focused on places on or near the train route from Seville back to Barcelona.