@rshov, here are a couple of other suggestions for you.
Marseille: I do like the city and if you prefer not to venture farther afield there are a few things you might like to do.
First of all, know that the ship does not dock right in town. There is (or at least used to be) a free bus service from just outside the port gates but to be honest, there are loads of taxis and the last time we were there it was about 20 euros each way in a taxi. There are marshalls organising the queue so it's not a free-for-all like you find at some ports. If you take a taxi, you want to tell the driver to take you to the Vieux Port (which means Old Port) and you will be dropped at the taxi rank there, which is nicely central and from which you have several options.
There is a free walking tour from the top end of the Vieux Port which my daughter has done and said was very good. No pre-booking was required for this pre-Covid and there were normally two separate daily tours, one in English and one in Spanish. However, at the moment you do have to pre-book and there appears to be only one bilingual tour. Anyway, you can browse their website here: https://marseillefreewalkingtour.com/marseille-free-tour/
Right by where the taxi would drop you is the terminus of the Petit Train (Little Train), which covers several routes. The one we did takes you around the port area and up to the Notre Dame de la Garde Basilica on a hilltop overlooking the city. This is not a HoHo service. Everybody has to get off at the Basilica and then you catch another train to complete the circuit. Tickets for the train can be bought from one of the agents working the queue. I can't remember how much it cost us but it wasn't expensive and it was an enjoyable trip.
Here's the Petit Train website: http://petit-train-marseille.com/en/home-7/
Unfortunately the Basilica's website is not working at the moment but you can look it up on Google and you'll get hits from the big travel sites like TripAdvisor and Lonely Planet, etc.
If you enjoy museums, MUCEM (Museum of Civilizations of Europe and the Mediterranean) is also very close to the Vieux Port. They are currently closed, again because of Covid, but you can see their website here: https://www.mucem.org/en/your-visit
I don't know if you know, but Marseille is famous for its soap (savon de Marseille) and there is a soap factory/museum (Musée du Savon) on the opposite side of the Vieux Port from where the petit train departs. Unfortunately, the website appears to be only in French, but here is the link to it anyway because it has a short video of the museum on the site: https://www.savon-de-marseille-licorne.com/le-musee-du-savon-de-marseille-vieux-port-de-marseille
My daughter visited this too. There are three options: just visit the factory shop - no charge, pay only for what you buy; visit the museum - entry fee includes a bar of soap; visit the museum and the factory - entry fee includes your own personalised soap (you can see them doing this in the video).
Here's a photo of my daughter's:
So that's it for Marseille.
On now to the other port I have a recommendation for and that's La Spezia.
Yes, you could go to Florence from here but it's a long way. You'll be spending ages on a bus and when you get there you won't have time to even scratch the surface, let alone do the city justice so, unless you're really enthusiastic about architecture and history and know you won't get another chance to visit, I would recommend giving it a miss.
La Spezia is the gateway to Cinque Terre: https://www.cinqueterre.eu.com/en/ and Cinque Terre is unmissable.
If you're reasonably mobile you can skip the expensive cruise line excursions and do it yourself by train. You can walk from the port to the train station in about 20 minutes. Inside the train station there is a dedicated Cinque Terre ticket office with very helpful English-speaking staff. They will sell you the train tickets and give you a free map and timetable. There are reduced fares for (if I remember right) 65 years and up. You can also buy souvenirs or a little guide book like the one in my pic.
You must validate your ticket by sticking it into one of the yellow machines on the platform and then you're good to go.
It works a bit like a HoHo bus; you can get on and off the train at the different stations along the route, spend some time in each village and get back on the train again at the end. We have done this twice. The first time we got off the ship quite late so we didn't make it to the last village, Monterosso. The second time we used a different strategy. We visited the first village, Riomaggiore, which had been our favourite on the previous trip, and then went all the way to Monterosso, where we spent a bit longer and had a tasty panini lunch at a beachside restaurant. If you enjoy beaches and think you might want to spend some time there, it might be worth sticking a towel in your bag and wearing a bathing costume under your clothes.
Doing this had an additional benefit. The trains get quite busy in the afternoon with people making their way back to La Spezia. Since Monterosso is the last of the five villages, it's the first one on the way back, so we got seats on the train. From the second village onwards, it was standing room only. That said, the total journey time is only about half an hour.
Anyway, apologies for the length of this post, but I wanted to give you plenty of information in the hope that it would help you in your planning. Feel free to ask any questions; if I know the answers, I'll be happy to respond.