Now that this thread has come alive again:
@MariaSP and any other Spanish speakers living in Spain, what would you use or advise a foreign pilgrim with only a smattering of Spanish to use in these situations as personal address:
tu or
usted?
bus driver in local bus; or taxi driver
cashier at small supermarket; or salesperson in El Corte Inglés
staff at reception desk of small hotel; or casa rural
Let's say everybody involved is younger than 70 - or feels like this - but not younger than 30.
FWIW, my policy is to avoid
tu and
usted verb forms as a matter of principle when I am not certain; to wait and see what the other person uses; to stick to my usual habits as to
tutoyer and
Siezen and
Duzen in French and German but things are changing there, too, and are becoming more informal.