I did some research on this, because I wondered why people ever brought cash for a tip, when you can sign the slip. Our first 2 cruises we signed the slip each time, because it just seemed easier than bringing cash. When I looked around, I found a thread where someone directly asked a room service attendant what is preferred and finally pulled an answer out of them. Apparently when you sign the slip, the tip is split between people, and it comes later. When you give cash they get to keep it all, and immediately, from what I remember. So I will be brining cash for future cruises.