Oh I forgot to provide input on your question " .. any advice on places to stay in Rome also welcomed …"

Since a cruise is your final destination, I highly recommend taking a look at Fiumicino.
Fiumicino is a small fishing village minutes away from the airport.

If you look at a map:
the airport is in Fiumicino
Rome is west of the airport (45+ min)
The cruise port is in Civitavecchia due north of the Airport (45+ min)
It is triangle.
We chose to stay in Fiumicino and cut off a leg of the triangle.

Hotel Tiber provide great (but simple) accommodations. The rooms were clean and had a great view of the mouth of the Tiber river.
The seafood in village was amazing, and walking along the harbor watching the fishing boats unload was a blast.

Great place to chill for 24 hours before your boat ride.
Or
After your boat ride on the way home.

The Hotel Tiber also arranged transportation from the hotel to the cruise doc in Civitavecchia.
Do not remember what it cost but is was around 100 euros for 6 of us.

I would definitely consider this an option to start your cruise.
Here is our blog entry for that day - https://15daysta.blogspot.com/2021/11/time-to-go.html