I don't know how long your cruise is, how old your kids are or what ports you are visiting, but if you visit PV on the Mexican Riveria, swim with dolphins is a must. Book early. Kids will never forget.
tnt I don't know which line you are on, but with Princess and our two grandaughters, at the time age 8 and 11, the childrens program on the ship was outstanding. The kids had their own dinners, allowing us to dine by ourselves. and the after dinner programs were very good with the children that allowed us to see many of the shows. After swimming with the dolphins in PV, in Matzatlan we took a city tour that included the native indian flyer program at a stadium in the golden zone. Buy the kids some things from Senor Frogs, big in that city. In Cabo. the visit is not long, grab a boat at the tender pier and visit the arch, then shop along the marina, or walk over to the town.
In PV, there is an excursion that takes you out to a resort, forget the name, but they have pools, waterslide, even a zoo. A family we traveled with said that was fun. I've also heard that the priate boat ride with pirate show is fun for kids. Yours are the right age for the dolphins encounter or swim (mine are too young so we haven't done that yet. Cabo you can take a boat excursion or just go shopping. Mazatlan is a big kind of dirty city so look for an excursion that takes you out of town or to a beach resort, unless you like to shop.