I was in a Neptune and sent in laundry 3 or 4 days; each time it was returned with a note naming the person who did the laundry (always the same person). I left a cash tip for her with the Neptune Concierge and submitted a compliment in the app.
I also gave cash tips, in addition to the gratuities, to my Neptune concierge, my room stewards, dining stewards, and 2 casino beverage waiters who never let me go thirsty! I also sent in compliments via the app for the casino waiters and dining stewards; the Neptune Concierge thanked me for sharing my feedback.