I used ITA (see our new user thread top of this forum if not familiar with it), stay ~ 3 weeks, departure window from late July + 30 days. Sample fares …

New York – Ireland. $748 rt total JFK-SNN for example (Air France, op by Delta).
Boston – Lisbon $922 SATA.
Newark – Paris $687 Air India.
Newark – CPH $822 SAS
Newark – FRA $678 Continental
PHL- MUC $770 USAir
IND-MUC $882 USAir

As with the past several seasons, fares seem to dip a bit for departures from mid-August onward.