Consider non-
DCL tours. Much cheaper and/or much more for your dollar, smaller, more customizable. TripAdvisor is your friend. I usually spend time finding out what's available, contact different providers, and go with the one that seems to be the most responsive to what we want.
CruiseCritic has loads of info, particularly if you want to completely DIY it. Look under their Ports of Call section.
For Civi, I'd go into Rome - you can take the train, I bet DCL will provide a bus that will drop you off and pick up up, but you tour on your own, or find a small group or private tour (Joe Bananas, Rome in Limo, and others are reliable and have lots of experience with making sure you get back to the ship on time.) You can NOT do it all in a day. Decide what's important. The Colleseum? The Vatican?
I did not love Florence, but really liked Lucca, which is a couple towns further inland from Pisa, on the way to Florence. Very nice old walled city, with a wide park at the top of the wall. You can rent bikes from the train station and ride around the top of the wall, stop and have a stroll down the narrow streets, have a cappuccino.
Marseille is kind of boring, IMHO. Find a tour that goes into Provence or Avignon.
My family loves food tours. Some of our best tours were walking around, tasting street market food, learning about the culture. I can't give you an specifics for these ports though, sorry.