If your son & DIL will be leaving from NWNJ or any of the greater NY airports in July, it will be expensive. You are a generous father! You have no wiggle room with weddings, set dates or alternate less expensive destinations. Some of the many web sites have teasers if you "join" their club-
www.bestfares.com
The airlines will have holiday sales in Dec. for next year. OR, do you have access to frequent flier miles?
Example: BA thru 28 Nov. will let me use one half normal frequent flyer miles. PHX to Warsaw/Krakow Poland for only 35K miles and pay tax and fees. My airfare for '09 cost $430 each RT coach and 35K FF miles (includes planned stopovers in London).
GL
John_AZ