We had our honeymoon in Oahu last year in September - loved it even though we weren't able to venture to the other Islands.
We were prepared for the "Americanisation" that Oahu has in particular over the other islands but it didn't bother us, given that we're both fond of America and given that we've been to purer idyllic locations such as Fiji, Langkawi etc.
Waikiki is as commercialised as it gets and very expensive as you'd imagine. Food was pretty good however and the portion size typically American
Book or eat before 8pm or you'll be carrying a pager and waiting a long time for tables.
Pearl Harbour, the Missouri, and Arizona memorials are a must do, and are great experiences. The Polynesian Cultural Center is also a great day out, and you'll get to see a lot of movie locations on the way (50 first dates, Lost, Pirates of the Carribean, Pearl Harbor (obviously))
We also hired a Dodge Challenger RT and headed up to the North Shore for sunset at sunset beach which was great fun
The other things we did were Diamond Head crater walk which was good, obviously Waikiki and also a surf lesson which I thought I'd hate but our instructor was great and we both had a great time:
http://tygurneysurfschool.com/
Flying out is fine because of the excitement but the flight home is a total grueller. It was two stop on the way out and three on the way back which didn't help. If you are only stopping over one way - I'd have to say to do it on the way back.
Quite tired now but if you have any q's will try and answer tomorrow.