I have heard stories all ways. That the delivery person gets all the gratuity added, some of it and none of it. The service fee all goes to the hotel. I know its expensive ordering room service but I always tip.
BTW, I was at the Sheraton Buckhead last month. I wanted something to eat so I stopped by the host stand and asked if I could order something to take with me on a short trip away. Sure they said.... I ordered a Reuben sandwich and french fries. 45 minutes later the hostess handed me a styro box in a bag and the bill... including all the room service charges and fees and tips etc.... I paid the bill, gave no additional tip, and will never stay in that hotel again. I even got a JD Powers survery from that stay. That was the first one I ever replied to!
TW