Don,

I did the same math comparing Celebrity with RSSC adding tips and bottles of wine and water on a Carribbean itinerary.

To be fair, I had to compare a Junior Suite on the Celebrity Cruise and figure out the per diem using square feet as well. We too ended up bringing soda and water aboard that cruise because I could not justify paying $5.00 for a liter of water for the convenience. Once we did the math, I figured that if the fare came within a few hundred dollars per person, I was staying with RSSC unless there was a timing and/or itinerary factor that made the other cruise more appealing.