During spring break I stayed in a hotel in Maryland that seemed to have take a green intuitive. They put little cards on the bed about not changing the sheets, as well as has compostable plates, bowls, and utensils to use in the lobby. While I do think that this is a good start, the hotel could do a little better. While having compostble items is good, the hotel did not provide a compost bin, or any recycling bin. I found this interesting that they would not provide a place to compost compostable items.
As for the card, any idea to try and save water, especially in hotels, is a great idea. My only worry is thinking about who actually remembers to place the card on their bed when they leave for the day. Also, I dont think many people traving to hotels near airports stay more than one night anyways, so the card is useless.