Not really sure what suggestions to which you aspire, but here are a few:
1. Splitting the time between HNL and OGG is a good idea. But, it depends on what you would like to do. HNL is a big city, but the island of Oahu is varied, and there are many cultural and historical sites. On Oahu,you could stay in Waikiki if you desire a vibrant/busy lifestyle, or you could go to the Turtle Bay Resort or Ihilani (may be closed for renovation) for a more rural experience. A great choice for near-Waikiki and attractions, yet in a more peaceful environment is the Kahala Hotel.
2. You might want to go to the Big Island/Kona side. There are many, many fascinating geological and geographical aspects. The beach at Hapuna and Mauna Kea Beach resort is the best in the islands.
Happy Holidays!