Depending on where you’re coming from, I’d recommend longer if you can. We come from the east coast, and own at the Marriott Ko Olina. We always go for at least 2 weeks, sometimes 4. It’s a long day to get there, and summers have a six hour time difference.
Definitely don’t miss the swap meet at the Aloha Stadium! Younger folks will appreciate the fun stuff you can buy like amazing scented candles and soaps. It’s every Wed, Sat, and Sun, and go early as it gets hot on the pavement.
My kids enjoyed the Atlantis submarine at the Hilton Hawaiian Village in Waikiki, but it’s not a “must do”.
Right at the marina at Ko Olina, we took a boat trip to snorkel with spinner dolphins once, which was really fun. Even my youngest who was very young at the time loved it.
I lived on the windward side for a few years, so when we go back it’s mostly to relax and sometimes go back to places we liked to eat and walk around. But for a honeymoon, I doubt you’re looking for mom & pop places, maybe more fancy. Sad that Alan Wong’s is closing for good now.