Traveling to Cinque Terre - Monterosso

Having experienced both airports and the commute from each to catch trains, and looking at travel times to get to the Cinque Terre area I would fly into whichever airport has the least expensive air fare.

I agree with AI. Look on the Trenitalia website for train options. Rome Airport is Fiumicino. Milan's is Malpensa.

Trains.

Go for the cheapest flight.

Although Milan Malpensa is a bit closer to Monterosso than Rome Fiumicino (in terms of miles), however in terms of train travel time, the two are virtually equidistant from the Cinque Terre.

Besides flight price, you should also consider convenience of flight (from your home airport you might have a non stop flight to an airport rather than the other, for example), and also the overall itinerary of your trip, since you might plan to visit other places in Italy and not just going to the Cinque Terre. So, for example, if you plan to visit some other place in Central Italy (like Tuscany) it might make more sense to fly to Rome, while if you plan to visit some other place in the north (like Venice or the Lakes), it might make more sense to fly into Milan.

Thank you for your great recommendations/suggestions.
I will be flying out of NYC - non stop and will be spending
most of my time in the Cinque Terre area. I will look at fares and
train schedules to compare.