My wife and I took a few Carnival cruises when we lived in Oklahoma. We just drove down to Galveston and got on the boat there. I had absolutely ZERO interest in going on a cruise. I HATE guided tours, and canned vacations and things like that. I like to get out and just do my own thing. But my wife insisted and we went on a cruise. We both had a total blast. The food on the boat is fantastic! It's like eating at a 5 star restaurant every night. Get the late dinner. Sure, you have to be there at a certain time, but I didn't mind. I made sure I was there every night. The food is awesome, and you can have as much as you want! Yes, you'll put on some pounds.
The last cruise we went on, a few years ago, was tons of fun! We rode the Elation from Galveston. We went to Progresso, Cozumel and Belize. When we got to Progresso, my wife wanted to go see Chechen-Itza (Mayan ruins). I was NOT interested in the 2+ hour bus ride to get there. But she insisted and we went. I was picturing a Mexican bus with chickens running around. But it was a nice, air conditioned charter bus. Also, they sold Dos Equis for .75 cents each!!! By the time we got to the ruins, I was roaring drunk! It was a blast. I climbed the huge pyramid there. I could have fallen off and died. Nobody cares in Mexico.
When we got to Cozumel, my wife wanted to swim with the dolphins. It was expensive and I didn't want to swim with the dolphins anyways. But we did it and it was awesome! Those dolphins are amazing. I got to ride one like it was a motorcycle or something. Crazy.
When we got to Belize, we went snorkeling. It was a cheap trip, but it was incredible. They took us out to this island that looked like something on a post card. It was absolutely beautiful.
The ship is fun too. There's always something to do or eat. Just get a cheap room. We were only in our room when we just couldn't take any more fun. We'd go pass out for a few hours, and then be back at it! It's the best bang for your buck you can get! The only thing you pay for on a Carnival cruise, is alcohol, and the trips you can take when you dock.