We went to Hawaii for our 25th anniversary and went to 5 islands. That was 14 years ago. But some things haven't changed.
CONGRATULATIONS ON YOUR ANNIVERSARY ! ! !
The Polynesian Cultural Center is awesome. And they have a very nice luau.
The Arizona Memorial will bring a tear to your eye. Go on a senic drive around the island. Take the road to Hanah. There is a recorded tour that will give you the sights and history of the things you will be seeing.
There is a 14 mile bike ride (I think its 14 miles. It may be longer.) It starts high up on the mountain and you coast all the way down to the base of the mountain. I'd say I actually had to pedal a total of may be 200 yards. You'll stop for breakfast and then coast on. It left our hotel room at 2 or 3 am. We traveled to the top of the mountain and were able to see a FANTASTIC sunrise. Then they gave us the bikes and coasted to the base of the mountain. I know that getting up top be ready at 2:00 am sounds severe. But if you figure the difference between Missouri time and Hawaii time, you are actually getting up around 6:00 am. The view is well worth it.
We were there for two weeks. We went to a timeshare visit and they gave us tickets for 4 to two luaus, and a ticket for two to ride in a submarine (a fantastic experience) BUT DON'T BUY THE TIMESHARE. Its not a good deal. If you don't have a strong will and can just say NO!, then don't go. The entire time share deal saved us about $300 in entertainment costs.
We ate at Burger King and the like for breakfast and lunch (99 cent menus) and had nice dinners (lauas). We stayed at a hotel on the beach with a very nice beach front view. HOWEVER, if we would have stayed at a hotel adjacent to the beach front hotel, we would have paid about half the price and had a condo with a full kitchen and livingroom. We just wouldn't have been able to see the ocean. We were in our hotel for a very short period of time so not being able to see the ocean when we got up and just before we turned out the lights wasn't worth the extra money and not having the condo.
Hope you have a wonderful time. Good luck to you and yours.