Mousekeeping loves tips and it usually gets you extra towels, etc. We don't have a set amount but the standard for any motel is $1 per person per day. I kind of look at our room and decide how bad it is and how much they have to work around and go from there. Anything is appreciated! We also leave extra pop, water, whatever is still sealed behind. If they can't take it home they can use it in their break room.