As a travel agent and cruise specialist, I usually recommend doing a shorter tour as opposed to a longer tour with kids. The rides on the transportation can be long and boring for kids; I am not sure that the kids would be thrilled or impressed with the Panama Canal. It is a pretty grown-up interest, unless they are kids who love engineering and are often building things for fun, but it is a lot of talking and geared to adults' interests. The shore excursions can also get expensive, so I recommend taking a shore excursion only if you are very interested in the content and destination of the tour. Generally, I think that kids would be bored unless it included time at the beach, a stop for lunch. Maybe they can stay in the children's programs while the adults take the shore excursion?
Please feel free to e-mail me if you have any questions!