There is a good fare with American and United to Dublin from New York JFK, LGA and EWR and Philadelphia PHL to Dublin, Ireland at $528 round trip for departures in May, June, September and October. Perhaps, the even better deal is December holiday season availability at $644 to $700 round trip with United, American and British Airways. Alliance partner flights are available for many one-stop routings.
United Airlines Newark EWR – Dublin DUB (UA nonstop) – Zurich ZRH (Swiss) – EWR Newark (Swiss)
$644.16 round trip Tuesday December 20 – Sunday January 1
American Airlines New York JFK – Dublin DUB (AA nonstop) – New York JFK
$527.76 round trip Friday June 10 – Sunday June 19