We love cruising. We've been on multiple Royal Caribbean, multiple Disney, MSC, Carnival, and Celebrity. I can't say I've ever had a bad cruise.
We prefer more scenic destinations. Our favorite is by far Alaska followed by Canada/New England. However, those are only available at specific times of the year. Alaska runs from mid to late May through September and Canada is usually only available in the fall. We've cruised Alaska, Canada, Caribbean, Bahamas, and Bermuda. For us, our least favorite has been Bermuda. Our favorite stops for Caribbean cruises have been Puerto Rico and the Virgin Islands. We haven't been to Puerto Rico since the hurricane hit though.
Caribbean cruises tend to be lots of open sea followed by ports that look and feel exactly the same as each other. All of the Caribbean ports have the same shops operated by the cruise lines. Del Sol, Diamonds International, Cariloha, etc...
We've been on many RCI cruises. That was our first cruise experience and we tend to return to them. They have a decent distribution of age and family dynamics. Not all kids, not all tales of the crypt. We really like Disney as well. Its not as kid centered as most people think and I didn't feel like we were swarmed with kids. The service was terrific and food was great, but Disney is considerably more expensive.
Carnival has a reputation for being a much younger and crowd with an extreme party atmosphere. I've only been on one Carnival cruise about 8 years ago. It wasn't as bad as I expected. Overall, it was a good cruise. The whole ship did seem to take on a Disco party theme around 10:00 PM, but you could get away from it. I would still much prefer most of the other cruise lines I've mentioned though.
The one exception was Celebrity. Again, We've only done one Celebrity cruise. It might have been that particular cruise, but the atmosphere was enough to keep us from seeking out another one. It was a significantly older average age and some might suggest significantly more sophisticated crowd, but I would say just plain snooty was our impression. I'd still take it over a day at work, but given the array of other options, I would pick any of the alternatives first.