That would be very nice, we did one somewhat similar except for the part east of Italy.
My step daughter lives in Marseille, along with a couple other friends, so we've spent some time there.
We have not yet spent much time in Rome, so this would add some to that. We take a couple days before the cruise mostly to adjust to the time zone, and then a couple after to look around before flying back. My wife wants to stay the last two days at the Waldorf there, which "looks nice". All I really want is a place that is clean with good mattresses in a decent location.