"Pacific" doesn't really tell anyone what kind of place and diving you have in mind, you must have some idea what are looking for or where you might want to go? Keep in mind that a bit more expensive airfare may get you to a place where everything else is much cheaper once you're there, so you have to look at the whole package. Once you have some places in mind, start with any of the major travel sites and start plugging in places. Some of them will let you select "surrounding airports" so that you don't have to worry which airport near you works out best. I use travelocity alot, there is also expedia and others. Kayak.com is kind of a fun site for looking up airfares and playing with different options but I'm not sure how thay are with international coverage. You may turn up some options that are roundabout travel but cheaper. You might also search for "consolidator airfare" sites - of course a little research to make sure they are reliable is also a good idea. Once you narrow things down, see if a place is served by any airlines that the major travel engines don't show, and check into those airlines directly. You can always find some general travel sites for a destination or it's airport that discuss all the ways of getting there. Realize some destinations don't have many (or any) options, for example some places it's pretty much Continental Micronesia or nothing. (Actually, it's always good to check any airline directly as well, sometimes they will have better deals on their own site.)
If you're really inexperienced in planning this type of thing, you might look at websites for dive shops in your area and see if any of them have trips planned someplace you might want to go. Often they will be focused on the cost of the whole trip to get people to sign up, and they may do things like get wholesale airfares. PLus you will have built in dive buddies. Lots of legwork done for you, if they're any good at it. Or maybe instead you should research who are good dive travel agents that know about areas you might want to go, tell them a budget and let them plan it.
You say your wife won't go that far to dive - would she go that far if there were other things about the trip that interested her, like a nice resort, cultural attractions, whatever.
