Had a great end of the year kidless trip with my wife. It was our third Carnival cruise, but the first in 13 years (first one was our honeymoon). A few notes about our experience.
We got a cab from the Miami airport and asked him to stop at Walgreens to get a 12pk of Coke (as mentioned on this site). He informed us he would have to put us on the meter instead of the flat $24 fee. After paying $6 for the 12pk, our cab fare was $37. Okay, $19 for a 12pk...not a good tradeoff. Needed to drink 11 of them to break even, not including the time lost to shopping.
After checking in at the ship and making our way to the Lido deck for a cheeseburger, I got called back down over the PA. They needed to talk to me about my luggage. Crap, I'll bet they found the rum I carefully packed. Security met me at the gate, and escorted me to the X-ray machine. As it turns out, you're not allowed to bring handcuffs onboard! I explained that they were just toys, and he says, "I know" and smiles. Interestingly enough I could see the rum bottle in the x-ray machine right next to the handcuffs. They allowed me to remove the cuffs and all was good. Funny, embarassing, but good. BTW, I haven't told anyone else about this part. Anonymity is a good thing sometimes.

Skip the cokes, smuggle more rum and airline bottles of flavored vodka, avoid onshore excursions, pack your swimsuit in your carry-on so you can use the hottub as soon as you board.
We're now booking our fall break cruise with the kids.
If you don't enjoy the cruise, it says more about you than the cruise.