I come from a town so it is possible to find different surnames, some of them are originally Catalan and others Spanish. Actually it is easy to find a great number of family names from our country and other countries: Peru, Ecuador, Colombia, Morocco...
My family name is very common, González, at university there was a lot of students with that surname. It is difficult to find the origin of my family name but I think that it comes from the south part of Spain and also from Iberoamica. González is the second common name of Spain, after Garcia, which is the first one.
In my country we normally use Mr. Or Mrs. together with the family name in letters, when we meet someone we normally say the first name and then the family name but it depends on the situation. I prefer to introduce someone not using Mr o Mrs before, I normally say the name and surname.