One thing you'll definitly miss from DCL is the free coke and RCI is very aggressive about their alcohol policy. I have yet to have my luggage on 9 Disney cruises to be confiscated for one bottle of wine. But, I have only heard of a handful of people get away with it on RCI and I myself on my last cruise one the Navigator 1/10 had my checked luggage confiscated for yes one bottle of white wine for a 5 night cruise. It was a hassel and very embarrising, but luckily we didn't put up a fuss about it and didn't have to drag everything out of our suitcase to prove to them we only had the one bottle.
My very first cruise, years and years ago I brought bottled water onboard, but have since learned that their water is just fine for me and I usually just purchase a bottle to take when going a shore. I don't drink that much to merrit a wine package, so I am sorry I can't make any reccomendations on that one.
I loved the Navaigator as I did it's sister ship the Mariner. Going on the Allure this May, looking forward to that too.