Ditto for carrying my opened soap, shampoo, conditioner from hotel to hotel or even home until it is empty/used up.
I make a Green Choice even when there are no points involved. I put the DO NOT DISTURB sign on. It irritates me to no end when the hotel has a sign that says hang your towels if you plan to reuse them. I hang them and they replace them anyway!
I bring my own slippers and amenities (toothbrush, shaver etc). (Same goes for airplanes). Slippers can easily be worn for 3-4 months instead of 12 hrs! Also annoying when the hotel unwraps slippers and puts them by your bed during turn down service when I have no intention of using them since I have my own. I presume those go straight to landfill.
Water bottles is another pet peeve. Never use them. Bring my own and refill them from the 5 gallon container in the gym or preferably filtered water dispenser if available.