You dock in Hilo , Honolulu and Nawiliwili (Kuai). You tender in Lahaina.
In Hilo , look for a tour that offers the orchid farms, Lava Tree State park and the hot springs. One tour offers all that and some snorkelling too. On Maui if you are truly interested in the geology, don't miss driving up Haleakala Volacano and go to Iao Valley (and on the way to Iao stop at the rather commercial but still beautiful Plantation and take the tram tour best way to see all of Hawaii's flora and fauna in one place). Maui Ocean Center is another good idea. Do you overnight in Maui? If yo do, the best Luau by far is Old Lahaina Luau .In Kona , maybe take a snorkell tour that takes you along the coast. The zodiac boats actually back into some of the lava tubes at the oceans edge.
Going to the Arizona Memorial? Tickets are free but are first come first served. Get there very early to avoid a long wait. Even if you are on a tour, you don't jump the line.
Drive up the H3 to the Dole Plantation to see the pinaapple and cane growing areas.
On Kuai you will want to see Waimea Canyon. It is several hour ride each way. To get the most out of your day on Kuai consider an all day tour. They will take you to the canyon, to the blow holes on the coast, to Wailu Falls and the Wailu River and to The Fern Grotto. You will get to see cane fields and the like along the way. Let someone else do all the driving here and you will get the most out of the island.