Sodas-Bring these with you, wow what a savings, saw one person with beer packed...wish I would have thought about that!!
Overall ship-Cabin location on 9 and above-wonderful, close to all the outdoor activities and you can walk everywhere (elevators appeared slow at times). Shows-get there early, we were unable to watch one show b/c of lack of seating at both early and late show times. Lines-we were never the first anywhere so we never experienced any lines. No issues with seating at the pool-chairs on multiple decks so people were distributed around the ship. If you felt an area was crowded (lido), a trip to Lanai (6) would provide you a whirlpool area to yourself.
Cozumel-Booked thru carnival, Rays, was a shorter excursion, felt like Carnival was not sure what do to, easily could have taken a taxi and probably done a lot more for a lot less. But the total cost of the excursion was less than $160 for 4 people and the interaction with the rays was good.
Belize-Booked outside of Carnival, Cave Tubing. Would recommend you research the company so you are clear of their understanding of the safety standards, types of tubes they use and method of transportation. We used a large travel company and rode on actual car tire tubes with lights on our heads (others had rafting tubes and helmets). Also CK WATER LEVELS before you go-it was an "orange" for us-NOT SAFE, I would not put my family thru this again. It was an experience of a lifetime truly-the caves are unique but not a trip for someone who is not comfortable walking 2 miles and crossing a large body of water waist deep (somewhat like rapids). Several older visitors were hurt while we were there (tubes hit trees, heads hit rocks, etc). Also, the caves are at least 1 hour away via bus. Sounds like Chrystal Caves are always calm.
Roatan-utilize the ship's area, go toward the end of the island, past the pier, beautiful beach and you have it all to yourself. Not a water lover-Rent a cabana-very cool and offers you your very own private beach. We did not rent chairs and stayed in the water the entire time-it was amazing.
Costa Maya-Rented a golf cart and rode to the beaches about 10 mins away. Many of the beaches are free, you can rent kayaks, or have a massage on the beach ($20 for 45 mins or $10 for 30 mins, got cheaper the longer you were there). Restaurants galore. If you prefer to stay near the ship they have a senor frogs and as the day goes on-patrons become the entertainment-its hysterical!!!
Overall, for the price, you can't beat this trip. Two ports that you can just walk off the ship and enjoy the beach-without booking a shore excursion makes it an even better value.