I took my first cruise with my 4 children on the Carnival Pride over the Christmas holidays to Cabo, Matxatlan etc. and we had so much fun! A lot of activities to keep you busy and we were going from 7am to into the wee hours 12am every day.
TIPS: Plan to bring more dressy clothes than what you'd normally wear on a weekend as I brought more shorts and t-shirts and probably would have been better to bring casual pants and/or peddle pushers. Also, it's great because they have a Laundromat for ironing.
The food is excellent. Camera film is expensive onboard so bring your own ahead of time. Definitely get a drink voucher that gives you unlimited soft drinks for the kids as we tried to get away with just drinking the free lemonade on board and that gets boring drinking that and water after 7 days.