best arrival airport and train to Vernazza?

Pisa airport is closest. Delta has a nonstop out of JFK on the higher end of the price spectrum, otherwise connect from a variety of European cities, (Munich showed a lower fare for a date I looked at this summer).
At Pisa airport, take shuttle bus to Pisa Central station. There are trains to Vernazza every half hour or so. You'll change trains at La Spezia Central and it takes 1:45 using cheap regional trains. Milan would be second choice. There should be plenty of nonstop from EWR or PHI. About a 4 hour train journey after the 1 hour train form the airport to Milan Central.

roger,

I don't know all the flight options from Philly or Newark to Italy, but the two most likely airports to use would be either Milan (MXP) or Pisa (PSA). There are easy rail links from both cities to Vernazza but of the two, Pisa will be somewhat easier and quicker.

Delta appears to offer flights from both EWR and PHL to PSA, however those require either two or three separate flights with layovers at various points (JFK, ATL, FCO, etc.), and a total flight time of about 14 to 20 hours. I'm sure that wouldn't be a "pleasant" travel experience. You could also check British Airways as they appear to offer flights wit a short layover at LHR and a total travel time of about 12 hours.

Good luck and happy travels!

Pisa is closest.
The Delta flight JFK - PSA mentioned above is a seasonal flight that operates 4 days a week from June through the end of August. Since I'm not sure when you are traveling, keep that in mind. That is the only flight direct from the US to Pisa, all other options require a change at some other EU hub.
Pisa is connected to the following EU major hubs:
FCO (Alitalia)
CDG (Air France)
MUC (Lufthansa)
LHR (British Airways) - however this is only one flight pair a day from/to LHR (in the early PM) therefore it may not be feasible.

If PSA doesn't work out, before considering Milan, check also Genoa (GOA), which is just as close as Pisa to the Cinque Terre (from the opposite side).
GOA has no direct link to JFK, but it has more or less the same connections as Pisa to the major EU hubs.

Thanks everyone, this is helpful information. It will be tricky, because I'll be making arrangements for one couple to travel from Philly or Newark, one from NYC (Newark or JFK), and one from Toronto. We'll hopefully meet up without any flight delays and be able to hop on the train together to get to Cinque Terre!

Last trip, we flew into Florence, then headed directly to CT. It was about a 15 minute taxi ride to the train station, train to Pisa, changed trains to La Spezia, then 3rd train to Cinque Terre. If flights are on United, Lufthansa, or US air, you might connect in Frankfurt. Lufthansa had about 1 flight an hour to FRA to Florence, so in the event we missed our connection, catching a later flight would have been a non issue.

Since your group may be connecting through different cities, I'd recommend everyone make there way to CT on their own, and meet up there, once everyone's arrived.

roger,

Thanks for the additional information. One way to ensure that everybody arrives in Italy at the same time, would be to have all couples depart from the same airport on the same flight (depending on which one offers the best flight choices). How difficult would it be for any of the three couples to get to either JFK, PHL or YYZ so that everyone could depart N.A. from the same airport?

If departing from separate airports is the best option, you could establish a meeting point at whichever destination airport you choose (MXP, PSA, etc.). The couple from Toronto will probably find that Air Canada to MXP or FLR is a good option (change at FRA) or a flight with KLM (change at AMS).

Just a thought.....

Thanks again for all the suggestions.
One thought that I'm having now is that maybe we should all meet up in Pisa and stay there for one night -- this should allow some flexibility in case some flights are delayed, etc. And in this scenario we can see the sights in Pisa before heading off to CT together by train the next day. Any comments about that idea?

Roger

I also live in the PHL area and there are no direct flights from the airport here to Pisa. I would recommend you meeting in Pisa prior to going to the CT.Good luck!

roger,

You'll probably find that you have more flight choices to MXP, so be sure to consider that also. You could stay in Milan one night until the group is together and easily travel to Vernazza from there.