First vacation was to Oahu which I hated the worst. It is very crowded, traffic is bad, beaches were packed by 9am. Also, I'm a 5 star kind of person and the hotel (which I have purged from my memory) was not good. I enjoyed our day on the North Shore but other than that, I did not care for Oahu--it reminded me of going to the beaches in the Los Angeles area.
Second vacation was to Maui/Hawaii. We stayed at the Grand Wailea in Maui which is a gorgeous hotel/spa but did not care for the Wailea area at all. Not enough to do. I was bored, bored, bored. On the island of Hawaii, I did enjoy the volcano area but other than that, I was bored.
Third vacation was to Maui and we stayed at the Ritz in Kapalua. I think I might have enjoyed this vacation (hotel is gorgeous) except I was going through chemo so I sat on the lanai in the shade and read for most of the week. Since it was the third visit to the islands, my negative attitude was already in place.
For me, Hawaii would be a good weekend place but a week or more and I'm climbing the walls. Driving around and looking at scenery doesn't thrill me and I can only sit at a pool/on a beach for a short period of time.
I'm in the minority in my opinions so I would not let my comments deter you from going there.