We are a family of 5 (2 adults, 3 Children) travelling from New York to Boston on 2nd January via Amtrak. I am looking at using the Red Cap service however want to make sure I tip correctly, as we are not use to tipping in Australia. How much should I tip? I am hoping to be traveling with only 3 suitcases. Also far in advance should we arrive at Penn Station to catch the train? Many thanks.