Termini Station to Civitavecchia: Cruise Ship

You've left out some of what we need to know, so let me make an assumption: You 10 are flying into Rome from the US. You should not be arriving on the day of the Embarcation, but on the day before. That means you have five rooms in a real hotel. That hotel has a local travel services partner who has a big incentive to provide good sevices to the customers of the hotel. You may have to put down a non-refundable deposit for the van. Unknown factor is volume of luggage versus passenger space. 10 people are a big group, and cannot be treated like, say, two couples traveling together.

All that said, you haven't defined "best". Is that: cheapest, most comfortable, best for disabled grandmother, fastest, closest to the ship (many cars can't go on the pier)? It only costs a few Euro per person to take the 1 hour train to Civittavecchia. But that leaves you a mile from the port's pier-shuttle bus station.

Thanks for the quick reply.
We are flying into Rome on the 5th and staying in an Airbnb.

We are all about cheapness. We don't mind roughing it and like adventure. We are all healthy and can walk with luggage.
I would love to know how to use the trains for a few euros; we have already spent a fortune getting all 8 grown kids and ourselves there: I try not to think about the cost; ha, ha.
I went on the site to order train tickets and they are around 29 euros from Termini station to the cruise port.

We are also looking into transportation from FCO to Termini station which is close to our apartment.
This is our first trip to Europe with our family. We will be in Rome for two days before the cruise and two days after. We would so appreciate any extra direction and ideas of what to see, where to go and what to eat. I have been taking notes from the RS books.
Our cruise will be going to Santorini, Rhodes, Mykonos, Naples, Athens and Messina
We need to figure out the train to Pompeii from the port in Naples
We need to figure out the train from Messina to Baia dell'Isola Bella
We want to arrange for a shuttle to Oia, but we don't want to take the donkeys or gondola in Fira; We heard that the cruise ship drops its excursion passengers off at a different sight where they board busses. If this is true can we get off also and arrange to have a van waiting for us?
We love to swim and snorkel.

It would be great to hire a inexpensive boat to take us around at one of the ports: any idea.

Sorry for all the questions and thanks for your help.

You've posted your questions in the Russia forum. Those about Greece are better addressed on the Greece forum, and those about Italy should be posted in the Italy forum:

https://community.ricksteves.com/travel-forum/greece
https://community.ricksteves.com/travel-forum/italy

We are also looking into transportation from FCO to Termini station
which is close to our apartment... We are all about cheapness...

Answering just this question, shuttle bus may be your cheapest method from FCO. Tickets will be around 5 and 6 euro PP one way, and the coaches are air-conditioned and comfortable.

http://www.adr.it/en/web/aeroporti-di-roma-en-/pax-fco-bus

If you take one of the frequent Regionale trains from Termini, they are 5 EUR pp. They take anywhere from 1 to 1 1/3 hour.
http://www.trenitalia.com/tcom-en
If you are traveling after June 10, you will not see these trains on the schedule yet, so just look at the same day of the week and time you want to go within the next week. Schedules do not change a whole lot, if at all. The price is fixed, so no point in buying ahead of time, except maybe the day before to save time on your travel day. If you do, make sure the tickets are dated for the day you want to travel. And do not forget to validate each ticket in the stamping machine just before boarding. If you forget and get checked, it will be about a 50 EUR fine for each unvalidated ticket. That would make it a very expensive transfer.

Why this is on the Russia forum, I have no idea. But don't delete it as all your precious answers will disappear.

I neglected to ask the month and year of your trip. Here is a past post that may be of interest. You can use the search box top center or left menu to find other past answers. I also failed to ask if this is eveyone's first trip to Europe? Rome is a great place to start, but herding a group of ten is well beyond the scope of this newsboard. What happens when someone is buying a coffee on the platform and the train doors close with nine of you on board? What happens when the tough guy in your group gets in a foreign-language argument with an aggressive beggar on the gritty Circumvesuviana train to Pompeii? Is your AirBnb legal and reliable? (Disclosure: I find AirBnb to be harmful to local life and to local housing markets.)

We walked from the Civitavecchia rail station because we saw that we had just missed the bus. It was long, hot, and confusing. You are going to the port shuttle bus terminal, not to the secure area of the pier itself. You may have more choice at Termini than we did at Ostiense, but I would be ready with small bills in case you have to use a ticket vending machine instead of getting in a long line for a human ticket seller. Are five people each going to buy two tickets?

Pompeii is an ideal independent outing from Naples. But you have to allow time to get back without fail before the ship leaves without you. Have you ever used public transportation before? There is unpredictable latency in each change of "seat".