One more thing about Rome: the Romans were among the most grumpy, unwilling hosts I've ever come across.
I know tourists are a hassle. We/they make themselves comfortable, are loud, don't know how to move with the flow of the city, get too drunk, and are interested in the wrong thing.
Still, they got off their butts, spent hard-earned money and their precious vacation time in a place unfamiliar to them. And they leave behind money, enough in Rome's case to save the city from being a sleepy, run-down capital city that takes a back seat to Milan commercially and Florence and Venice culturally.
My idea is this: tourists should rate the friendliness and basic manners of the people in various destinations and impose a short-term boycott of the worst to make a point the tourist boards surely won't miss. If these boards have any sense, they'll start smile campaigns and abbreviated human being schools for people in the trade, and also make them more aware that these pesky tourists put food on the table, finance high-end mopeds, etc.