I would strongly consider getting the Chase United Cards (1 for you, 1 for your wife). That would give you 100,000 miles after first purchase, which is nice because you won't have to hit a minimum spend. 2 economy class tickets is 80K miles roundtrip, plus $20 in fees. That takes care of the flights. I checked the dates you posted above, and their seems to be good saver availability

Agree with the Hyatt card suggestion above as well. that gives you 4 free nights after first purchase.

Finally, I also concur with the above suggestion that you do not stay only on Oahu. It's fine, but IMO, you can't really experience what Hawaii is all about until you go to the other less commercial islands. Big island is my personal favorite, but Kauai/Maui are also very nice.

Good luck!