Sevilla, stay more that two nights!
Sevilla was so charming with it's narrow, winding streeets, beautiful Jewish quarter, and of course the historical/tourist sites. The Alcazar is one of the most stunning places in the world with amazing details on every wall and ceiling as well as beautiful gardens. Plaza d'Espana was stunning. Definitely a gorgeous city when lit up at night especially the cathedral and torre de oro. Highly recommend.
Insider Tip:Don't miss tapas- go away from the main squares/streets for the real deal