I traveled to Hawaii 12 times before finally moving to the Big Island.

Each island has pluses and minuses and which ones you like depend upon your activity level and whether you like exploring.

Oahu is small and filled with people. Lots of competition for your money, especially Waikiki and Honolulu. The north shore is surfing and beaches, however many are not easily accessible because there will be houses between the road and the water. Many places will be familiar if you watch Hawaii-50, or the many other shows and movies produced here.

Kauai is green and photogenic but a relatively small island.

Maui is a nice stay.

Molokai is VERY laid back and although a great place to visit, some might get bored.

I like recommending the Big Island because of its sheer size and variety of climates. Mostly rural, there are many varied activities like horseback riding, zip lines, hiking, snow sometimes and the volcano. You would do a lot of driving.

There are a number of "Wizard" books like Big Island Revealed and Oahu Revealed, etc. I was not impressed with the app for Android, but the books are excellent. You can probably find them at your local bookstore.

For a few days, almost any island will be a treat. If you can visit a couple islands, even better. You should understand that every island is different enough that you will not feel that you are on just another island.