train from Rome to Naples

Just buy them at the ticket counter at the train station - no need to plan ahead. It's a 3 hour or so ride - I don't know if 1st class is necessary..what does Rick say?

Actually, there's a very good reason to buy them in advance - you can save a ton of money by buying 2nd class tickets ahead of time on www.trenitalia.com The catch is that they are non-refundable.

The 3 hour ride is via a Regional train. Those tickets are never discount so you can buy at the counter at your convenience. However, the high speed train tickets can be purchased in advance at deep discount.

The time from Rome to Naples on the fast train is about 1.25 hours. If you are traveling on a set date, you can save money by buying the Freccia ticket (fast train) in advance, it will have a carriage and seat number on it so you don't have to validate it before boarding. Go to Trenitalia.com, you can print out your ticket (it will be emailed to you).

So, to summarize. We don't know what your preferences are, your traveling style or much more than your question. If you want large seats, compared to flying, plenty of legroom, either a table or pull down behind seat table, and big windows, pick second class on the high speed (Freccia or .Italo) train. It can be a bit louder in second class because there are more people and families in second class and they talk together. If you want super huge seats, only business travelers and rich tourists, and get there the same time, then pay the extra for first class. For such a short journey you might wonder if it is worth the difference in money. If you want to save money on the high speed trains get them well in advance, and treat them like a flight. You save money buy buying in advance but you have to commit to a particular date and time - changes and refunds don't go with the cheapest tickets. If money is no object just get to the station a little before it goes and buy a seat on the next available train - but you will pay the highest price. If time is of no concern, then you can pay the least with a walk up ticket for the all stops slow Regionale train where the prices don't change. They can be very crowded, often the airconditioning is non existent, the windows may be open, and you will hear very little English. In that case you might prefer first class with a little larger seat and less noise and perhaps less overcrowding. All those choices are there so you can choose which appeals to you and your pocketbook.