I have never been to the most of the cultural and historical institutions on Oahu (or elsewhere in Hawaii), but I still think Oahu is great, as long as you understand that Waikiki is a very densely developed beach resort, but Kailua and Lanikai beaches are underpopulated and beautiful (kayaking is great), the north shore beaches are gorgeous, Haleiwa is funky and fun, and the drive through the middle of the island is truly spectacular. I could easily spend 6 days on Oahu ( and have). I've done so on Maui and Kauai as well. They each have their charms.

add Shangri La to that list of things to do on Oahu. The Doris Duke Estate is a great tour. We have also done walking tours of China Town and found that interesting. Bishop Museum is another great experience. HNL is not my favorite place in Hawaii but it is close and easy to get to from the west coast and when we want sun, beach, palm trees we head over there for a quick trip if we can find a good deal. For longer trips 7 + days we head to Kauai...More low key and relaxing for us.

I love Waikiki!!! I most often travel solo so like to be where there's lots of people around, things to do, not needing a rental car. I understand it's not for everyone, but if it wasn't well loved and very popular with so many people... well it wouldn't be so crowded ;-)