In Madrid the most common names are Lucia, Marta, Andrea, Nacho, Alejandro, ... There are some names that come from other countries like Kevin, Jessica.
My family name is Sanchez. It is a very common surname in Spain and it means "son of Sancho". It comes from Castilla.
I think I only use surnames with a title for doctors. In other situations I use the firstname or the firstname and surname.