Many draw power continuously. Lower the waterbed heater temperature 10 degrees. Stop newspaper delivery. Use the air conditioner. You'll actually save fuel because you won't have to overcome the increased drag caused by open windows.
Airlines tend to arrange everything in little paper folders.
Tell the clerk you don't need all the packaging. Even then, make sure unused towels and washcloths aren't replaced and washed unnecessarily. Notify the housekeeping staff if the sink, shower or toilet is leaking or dripping. If you don't need the free shampoos and soaps, leave them untouched so the next guest can have them. Don't go crazy at the brochure rack, either.