In a couple of weeks our family is flying to Rome and then taking the train to Monterosso. I am wondering if it is necessary to purchase tickets in advance? We are arriving on 3 separate flights. If the last of the flights is late or it takes a long time to clear customs, we might not make the train if we have pre-purchased tickets.Also, how much time will it take us to get to the train in the airport. I have never been in the Rome airport. We are staying two nights and then returning to Rome. Can we buy the return tickets when we arrive in Monterosso?
You are wise to wait till everyone arrivals since you are dealing with three flights. The airport train station is a five minute walk from baggage claim. For there it could be as much as an hour to Termini in Rome. Thirty min train ride every 30 mins so if you just miss it it adds time. In Termini another 15 to 20 minutes to find your next platform and train. You can buy your tickets to Monterosso in the airport train station.
Whether you wait for all of your party to start heading to Monterosso is up to you. However, you can buy tickets in advance and go in stages if the earliest landers just want to get to the hotel. If you choose to wait for everyone to land you can still buy tickets in advance. You just need to account for time needed (2-2.5 hours) to clear customs and take the airport train to Rome Termini; where you can change out to a train bound for La Spezia. When you arrive in La Spezia you can buy tickets on the regional train to Monterosso; this train runs every 20 minutes or so. You can look up train schedules and routes from our rail page and you can book your train tickets in advance [www.ricksteves.com/rail]. When you search for the train routes or buying your tickets make sure to search from Rome Termini to La Spezia. You can always get tickets on the regional train that runs from La Spezia to Monterosso, but it is challenging to book this piece or look at the schedule very far in advance. Buena Fortuna!
The trouble with that time line is the big variable called immigration IF your parties are going through immigration in Rome. Posters have reported clearing immigration in 30 mins. Last May it took us over two hours to clear immigrations. Tack on another hour if you just miss the train to Termini. Your 2.5 hour time line just disappeared. With any train ticket when the train leaves the station and you are not on it, the ticket is dead. You cannot exchange it for another ticket. So in your situation I would wait until you see the whites of everyone's eyes.