It depends on the hotel. Most Resort properties include a service charge; however the Vail Marriott where I stay often for extended periods does not. When I am there, as I am now, I tip the housekeeper $5/day. The housekeeper from 2 years ago remembered me when I saw her walking down the hall. The down side is, she was very disappointed that I was not in one of her rooms. I got the impression from my current housekeeper and the one from 2 years ago that people generally do not tip.