Weinman canyon was worth the visit but perhaps not again. It's grand but still not the Grand Canyon. We took the ship's excursion and got a wonderful bus driver (Don), which made the trip very enjoyable.
Pearl Harbor was a must. We got there around 9 (taxi) and Arizona was already selling tickets for 2pm. We skipped Arizona but toured USS Bowfin and the Mighty Mo. Surreal experience. Waikiki is nice, but not much different from Miami, etc.
Hilo was our busy day. We used Mary Lou's tour service and could not say enough good things about it. We got to see the following for less than half the price the ship would charge: Banyan drive/vicinity, Volcano National Park (including Thurston lava tube), winery, orchid farm, nut factory and the garden behind it, rainbow trees, rainbow falls, black beaches and sea turtle!! It was a long day (from 9 to about 4) but totally worth it.
We took the bus (#25 route I believe) from behind the movie theater. It cost $1 per person and runs between the port to Whaler's Village/Kaanapali beach (better have many $1 bills ready). Buses leave the port at half past the hour and leave the beach on the hour every hour. Beach was beautiful. With plain goggles you could observe plenty of marine life.