Need advice on itineraries for Italy cruises

Are you tied to wanting a round trip Rome cruise?

Also- what cities are your priorities?

Not necessarily. I looked at NCL cruises that departed out of Barcelona and ended in Rome. But they were a more expensive and later in May, so I started leaning toward the Rome to Rome cruises (above). But I'm open to suggestions!

Dumb tourist answer = I have no priority cities. LOL. I've never been to Italy, so Rome is key. After that, I'm not familiar enough with the region to say. I just want to see the sights and eat lots of pasta.

For me personally, I like #1 and #3. IF by Marseille (Provence) they mean you dock in Marseille and have Provence excursions, excellent. (#1) BUT for #3 Villefranche is a charming town and you most likely have opportunity to see Nice. Both have Florence, a must. Then #1 has Genoa - excursion to Portofino. Lovely! But #3 Naples - never been there but I hear wonderful things.
And Barcelona is wonderful as well! I'm not help at all! I would look at pictures of the towns I mentioned and see what feels compelling. BUT you will LOVE Provence!

I'd vote for #3:
La Spezia: a little less than 30 min walk to the train station, then short rides to Cinque Terre villages. I would head for Vernazza of the five towns for first time visit. Views from the harbor of Riomaggiore are also spectacular. You probably wouldn't have time to hike the trail between the towns, but the views of Manarola from the trail are spectacular. I think there's a restaurant in Manarola that offers a similar classic view.
Santa Margherita: 15 min ferry to Portofino. Walk up to Castel Brown (opens 10 AM with small entrance fee), not for anything in the castle, but for the spectacular views overlooking Portofino and sea.
Ajaccio: Never been.
Villefranche: Absolutely lovely, if you like charming, narrow alleyways between pastel colored buildings with pretty shutters, arched pathways, etc..
Naples: Our best daytrip from Naples was walking from the cruise port to the ferry port (I think, Calata Porta di Massa which is a 10-15 min walk from the cruise port)
. Hop on the slow (one hour) ferry to the tiny island of Procida. The slow ferry (vs. hydrofoil) allows you to stand outside on the ferry with a great view of the pastel colored buildings of Marina Grande as the ferry approaches. Walk across the tiny island (not that far, maybe 30 min) to the viewpoint overlooking Corricella Harbor (Belvedere Terra Murata). Magical! We made it to Corricella Harbor and back to our ship with plenty of time left during our 8 AM to 5 PM port stop in Naples.
Regardless which cruise you select, you will have a great time! Wish I were going!

I would pick #3, and enjoy addl days in Rome. We did a cruise from Barcelona to Rome and loved it.

We stayed in town of Marseilles and had a great time, saw Nice, did a Portofino and small towns bus/boat tour, visited tower of Pisa and had a Tuscan countryside lunch with wine. We also did a morning tour of Pompeii, had a great pizza in Naples (just a few hours wait) and more.

I’d just keep my excursions to shorter drives from port so you don’t spend all day driving to a more inland place. If you want to prioritize inland- I’d not do a cruise.

Since you say your priority is Italian ports, then #3 is the obvious choice. But add as many pre and post cruise days as possible into you trip for extra days in Rome and Florence, and possibly a bit more of Umbria and Tuscany.

Besides, I have a soft spot for the Constellation.

Thank you for everyone's input!

I would choose #3 for sure. I have cruised the Med on Celebrity and it was great. The #3 itinerary has "more Italy". I wouldn't go to Florence from La Spezia, since you will be going there on your own. Like another poster said, use that day to see Cinque Terra. Santa Margarita is nice, and close to Portofino if you want to see a bougier location. Naples is a wonderful port with so many options. My favorite is to hire a driver to go to the Amalfi Coast. You can skip Naples unless you like the gritty city experience. Pompeii is close, and you can make it a stop on the way to/from Amalfi Coast, IF you are willing to spend just enough time there to see it (that's what we did, in 1.5 hours we got enough).
I recommend you do your Rome and Florence few days BEFORE the cruise. There is so much to see, you will be beat, and then you can relax on the cruise.
I would fly to Milan or Florence (depending on price and convenience for you), train to Rome, and fly home from Rome. I would use the cruise line for your airport transfer, because they'll make sure you are on time, and it's not close (port to airport).
Have a great trip.

Azamara has an Italy Intensive cruise next spring that might interest you. It’s a smaller ship so you won’t find the water slides and licensed shows of the mega ships, but the smaller capacity is what drew me to them. Check out the itinerary
https://www.azamara.com/cruises/jr270505-010-italy-intensive-cruise-venice-sicily-amalfi
I hope this helps.