Maui No Ka Oi - Maui is the best… or at least it was when I lived there.
Hale-Akala (House of the Sun) is a must. The locals told me how they would drive up to the 10,000+ crater when it snowed & make snowballs, then bring them down and have snowball fights.
Hale-Mahina (House of the Moon / West Maui Mountains) is smaller, less traveled, very lush because of all the rainfall. West of Wailuku, Io Needle is a nice little hike.
Depending on whether a storm is coming the north shore by Paia (NE of Kahalui on the Hana Highway) can be incredible, waves bigger than you’ve ever seen anywhere. At night it’s really humbling, the power of nature. Most of the time the surf is 10 feet or less, but I’ve seen 40 ft waves, look on Youtube for surfing competition at JAW where waves can be 90+ feet. It’s wild.
A ton of people drive to Hana on the east end - long, winding drive, places where it’s one lane, rain forest with lots of waterfalls hanging off the mountain. On the way back, I’ve just made a circumnavigation and went on the south side of Haleakala, which is windswept, a few hippies live there.
Makena beach south of Makena / aka “Big Beach” is a really big beach, visible from space.
Over in west Maui, Lahaina has a lot of historical stuff, if you keep going to west to Kapalua, a beautiful vista where Lanai and Moloka’i are visible. I would do the circumnavigation of west Maui - go past Lahaina and just keep going, all the way around back to Kahului.
Not a ton on Lanai, lots of golf, lots of beaches, an old ship wreck on the north shore.
O’ahu has a ton of stuff to do - east shore up to north shore is the opposite of Honolulu.