What Kerouac2 writes almost perfectly describes the situation in Mexican Spanish. Always use "Usted" (and/or its verb conjugations–quite easy in Spanish as it has the same conjugations as he, she and it–only "tú" has its own special conjugations) with strangers unless they are obviously children.
Outside of the major metro area of Mexico City, few, if any, will ever ask you to change to "tú". I've known my wife's parents for 10 years now and have been made to feel a complete part of the family, yet I have never been asked to "tutearme", i.e., use "tú" when addressing me.
Even in the foreign tourist areas, you will find that this brings MUCH bigger smiles (minor bureaucrats such as customs and immigration officials particularly respond positively) and more respect for YOU from the locals.
I find it curious that, unlike English, the drift in the Spanish-speaking countries is towards the use of the familiar in place of the formal/respectful. English went exactly the opposite way, as "you" was originally the formal/respectful and "thee" was the familiar or informal. I have my own fairly strong ideas about why this happened, but I've really not researched the matter.
Edited by: mazgringo

