I am perfectly happy with the ice tea, lemonaide and coffee you can get onboard, so I rarely order a coke. I do however, sometimes order a glass of wine with dinner or a cold drink if out by the pool. Also, eating all meals onboard is enough, don't need to eat in ports...It does save $, even though I don't not eat at ports to save money, but I find plenty enough food to eat onboard, I am not the least bit hungry when out in ports or doing excursions.
For the gamblers, limit yourself to so much $ per day and stick to that.
After I loose $20 that is it for me, not much of a gambler and don't like to loose. I would rather shop than spent it in the casino.