Turn down service is actually available in standard rooms at all the deluxe resorts. It just happens automatically at the concierge level instead of having to request it through housekeeping.
I do tip turn down service at a rate of $1 per bed, or a $2 minimum. In addition to turning back the covers on your bed, they will also replenish any towels or toiletries that you used since housekeeping made up to your room earlier in the day. They'll remove trash and with my children, they always took a few extra minutes to arrange their stuffed animals in very cute positions. We'd find them sitting in bed reading a book, holding the tv clicker and watching the resort station, etc.
I make up envelopes similar to the "mousekeeping" ones and just mark them for turn down service. If we are going to be out of the room for the whole day, I generally leave the housekeeping envelope with the towels and the turn down service on the nightstand by the bed.
Tammi