Been to Kuai, big Island, and Oahu.
Oahu great for city vibes. Waikkiki is nice but a tourist trap. Did mainly touristy stuff there but it was cool - pearl harbor, north shore, waikikki.
Big Island and Kuai are way more chill. We flew from Oahu to Kuai, nice little 20 min flight with great views.
I kinda get the vibes that locals don’t mingle too much with mainlanders. Probably tourists get a bad rep, but some of it is earned. Saw some locals cuss out a 10 yr old boy for touching a sea turtle. Big no no over there.
Local food-you like spam? Try some poi it’s great lol. Seafood is awesome if you are into that.
The coolest things I have done in HI(besides golf ha ha) are see the lava, snorkel, and rent mopeds on big island and cruise to all the little beach spots. Kona side.
Hiking is dope on Kuai. No snakes or predators. Kayaking and hiking to waterfalls if you are into that.

Edit: also check on the covid restrictions. I believe there are quarantine and/or testing required right now. We might go in late July to big island.