We are going on our first Disney Cruise January 28th on the Wonder leaving out of Miami!! We're flying into Ft. Lauderdale the night before and staying at the Westin Diplomat in Hollywood, Fl (got a great rate thru hotwire!). Based on the great reviews, SAS transportation is picking us up Monday morning at the hotel and dropping us off at the Port of Miami. There's 8 of us total (4 adults and 4 children) and we were quoted a rate of $13/pp to be paid to the driver. What is a customary tip for a shuttle driver? Thank you!