I have arranged airport transfers through the apartment rental agency I'm using. Each transfer costs 40 euros, and I don't mind paying that for the convenience of the service. (PLEASE DON'T RESPOND WITH OFFERS OF LESS COSTLY TRANSFERS!!)
Do the drivers generally expect a gratuity on top of that set fee? I hate to sound cheap, and I don't like to leave a bad impression of Americans when I'm overseas, but I've had people decline tips in some countries. Any advice or guidelines will be appreciated.