Having a personal stake in the matter, I definitely prefer the "'s" even when the singular noun ends in "s". And I don't even notice that the three "s"es in a row in "boss's" is weird; it looks perfectly reasonable to me.
Part of my reasoning on this is that I pronounce the possessive "bosses", not "boss", so it should have an additional "s" compared to "boss".
no subject
Part of my reasoning on this is that I pronounce the possessive "bosses", not "boss", so it should have an additional "s" compared to "boss".