If you can get 2 weeks or more, go to Hawaii.
I honeymooned there (on 3 islands) and we were hooked, have been back 6 times in 10 years. We also have been to most of the Caribbean Islands, and while they have their own charms there is nothing to compare to Hawaii.
It is truely a destination you will remember your whole life. Most people start doing calculations on how many jobs they would need to move there after their first visit. Given that your young, you havent been spoiled by first class yet, get a pair of coach tickets flying into HNL(oahu) and back from OGG(maui), catch an interisland flight after a week and try both islands.
It is totally worth the 10 hour flight, you will go back again. If you can get more AA miles go first class, it makes a big difference on such a long flight...but be warned you will be spoiled and won't want to do it in coach again.
You and your wife can dive or just snorkel (best stuff is in the first 35' anyway) Hawaii has more varieties and more fish than i've seen in most of the carib put together. and you can go right from the shore.
So many other things to do and see, and no passport needed.
Only worth the long flight if you can go for 2 weeks or more...otherwise Caribbean is your best bet.