Places to see in Spain - Granada, Toledo, Seville, Segovia, Avila. Surprisingly, Madrid is not tht interesting, with the exception of the Prado museum if you like art. I don't know northern Spain, so can't make any suggestions. Granada has the Alhambra - fantastic! The whole city of Toledo is like a museum, you can walk across Toledo in 30 or 40 minutes.
A great country to tour.