Train from Rome FCO to Pompeii

Let me see what I can clear up. Trains in Italy rarely if every sell out. What sells out quickly are the discounted tickets. The three fares are - Super Econ, Economy, and Base. The first two comes with restrictions regarding changes - no changes. The Base is always available and you will have no problem getting a ticket after you arrive. Tickets are available. Not sure what you are doing or seeing. Double check your dates and times. The Circum... is the local, private line to Pompeii. Cannot be bought through Trenitalia and no reserve seats so buy when you get to Naples. You will need a separate tickets to Termini from the airport, Rome to Naples, and Naples to Pompeii.

Thanks Frank....so you think even the fast train wont sell out from rome to naples? How can I figure the cost of what each segment would be. I tried the Rick Steves link and it seems if I booked online with that site it would be about 50-70 with 70 being if we took the one option that allowed a one time change. How much more would it be if we bought them all the day of? Trying to weigh if its smarter to just go from munich to naples for about 70 although it leaves Munich at 6.55 am so that would be super early morning. Unfortunately we already have a munich to Rome ticket that is nonrefundable but the new ticket might be the same price as the train and be more convenient except for the crazy early departure. Our thought was to get into Pompei late afternoon, check into our hotel and then go have dinner in Sorrento and then tour Pompeii in the morning before heading back to Rome

The base price for Roma Termini to Napoli Centrali is 45 EUR per person standard class (AKA 2nd class). Economy and SuperEconomy prices are less, but depends on departure time and day. Garibaldi station is where the Circumvesuviana trains to Pompei go from and it is connected to Napoli Centrale.
On the afternoon of August 31, there is a fast train to Naples about every 30 minutes from Rome Termini, and slower IC and Regionale trains as well. So it would be very unusual for them to be sold out. Each train has several hundred seats.

Since there are 8 of you, it may be less expensive for you to take a taxi or two from FCO to Roma termini.

Frank is right, trains rarely sell out. It sometimes happens before/after long weekends and in early/late August: when italians go on holiday and when they have to go back home to work.
If it happens, keep in mind that there is another competing company that runs high speed trains from Roma Termini to Napoli Centrale: www.italotreno.it/en . Google image their logo and, if you need it, look for their counters at Termini.

Italo would be a good Plan B, and I bet that even purchasing at the last minute Italo will have cheaper tickets than Trenitalia for sale.

Plan C: purchase a Trenitalia's Regionale ticket from Roma to Napoli. Regionale trains have no reserved seats, hence they can't sell out. It wouldn't be the best journey of your lives, it takes more than 3 hours, but it would be a way to reach Napoli.

Garibaldi station is the underground level of Napoli Centrale. Two trains leave from those tracks to Sorrento calling at Pompeii: the slow, old (and crowded) Circumvesuviana and the newer Campania Express.

PS On trenitalia.com/tcom-en I couldn't see "not available" trains on August 31. There are many SuperEconomy fares left.

chefdanika, I don't want you to change all your plans, but it's a little unusual to lodge at Pompeii. If you are going to be in the area longer, it's most common for people to stay in Naples or Sorrento and take the Circumvesuviana (no reservations, commuter train) with no luggage, to Pompeii for the amount of time they want to spend in the ancient site. On the other hand, for budget travelers, the actual Amalfi Coast (like Positano) is so isolated from Pompeii that it's common to see Pompeii on the way to the Amalfi Coast. I personally prefer to have unlimited time at Pompeii, so we spent a whole day of our five nights in Sorrento at Pompeii.

(The ancient site has excellent bag checking, don't think I'm creating any doubt about that. I just don't want you to spend a whole night in a place where there is little to do after the site closes.)

Rather than the frazzled dash to Sorrento/Pompeii, why not stay in Rome and go to Ostia Antica.

It will give you a similar experience without the wear and tear of dashing back and forth from Rome.

You will enjoy your days in Rome more if you are not "dead tired" when you start there.

Joe, I've never been to Ostia Antica. Are there any frescoes like those at Pompeii? If I got it right, Ostia was like a blu collar port city while Pompeii was the Orange county of ancient Romans.