I wouldn't skip any of the ports mentioned if it's your first time there.
For a second visit I would probably skip Marseille, especially since you're being shuttled into town and back.
Once you've seen the tower in Pisa you are obviously not heading there again either.
You're disembarking in Civitavecchia (Rome) so that's not an issue, but if you were merely stopping there then I would recommend either actually going to Rome or visiting some of the nice, nearby villages. Otherwise Civitavecchia itself is one of those places not even worth disembarking for.
In Mallorca you can always take it easy by just strolling off the ship and heading in a westerly direction towards a big shopping mall nearby. The kids will surely love it and you can stock up on snacks and all sorts of stuff whilst enjoying a nice walk there and back.