I grew up in Hawaii and have lived most of my adult life in Hawaii. Here are some limited comments. Each island has it's own "personality" and I suggest that you do some research before making your decision. The texture of the sand which is eroded coral or lava is very different from the sand along the St Petersbug beaches.
Oahu: The population center. Lots of history in/around Pearl Harbor and Hickam Air Force Base. Note: Visits to the USS Arizona Memorial are currently limited to the Visitor Center.
https://www.nps.gov/valr/index.htmKauai: Called the Garden Island because of abundant rainfall. The average annual rainfall on Waialeale is 450 inches. As someone else noted a boat/helicopter ride to see the Napali Coast is well worth the time/expense.
Maui: A visit to Haleakalaa to see the sunrise is spectacular but access is limited during sunrise.
https://haleakalacrater.com/haleakala-sunrise/ If you choose to drive to Hana, don't forget that you have to drive back. To my eyes, the white sand beaches in the Kaanapali area are impressive-Much better than in Waikiki.
Lanai: It used to be dominated by pineapple fields. That industry has been replaced by high-end resort hotels.
Molokai: Kalaupapa is located here. Read the story about Father Damien. If you decide to visit Kalaupapa, consider taking the mule ride down there. You could fly there (expensive) or could walk (going downhill is OK, returning is more challenging)
https://muleride.com/ Since not many people live here, there are no permanent stop lights.
https://themolokaidispatch.com/islands-first-temporary-stoplight/Hawaii: Yes, it can be confusing. Many here call it the Big Island to differentiate it from the name of the state. In the winter, you can go from black sand beaches (not many white, sandy beaches here) to a snow-capped mountain top (Maunakea). The Kilauea volcano is no longer active but you can see where the recent flows entered the ocean. Rainbow Falls is spectacular after a big rainfall. Akaka Falls is something to visit.
http://dlnr.hawaii.gov/dsp/parks/hawaii/akaka-falls-state-park/If you drive to South Point (I'm not sure that rental car companies would be happy if you did this.), you will be at the southern-most point in the United States. It is further south than Key West.
Kahoolawe: The Navy used it as a bombing target. Most of the ordnance has been cleared. I suggest that you not visit this island.
Niihau: It is privately owned. You can visit only if invited by the Robinson family.
I hope that these limited comments will lead you to internet searches which will help you decide whether Hawaii is worth visiting.