Your options for Hawaiin cruises fall into three basic catagories.
1) Roundtrip from the West coast. Usually 14 days or so with 4 sea days in each direction to and from and then 6 days of stops, (Kona, Hilo, Maui, Kauai, Oahu) usually one or two of those overnight.
2) a one way (to or from ) the west coast. 4 sea days and usually 5 , 6, 7 port days. These are often repositioning cruises as ships head to or from Alaska in Spring or Fall.
3) The "based in Hawaii" cruises offered by Norwegian.
Option 3 of course involves roundtrip airfare to Hawaii. , Option 2 will involve one way airfare to Hawaii, option one, round trip airfare to the west coast.
The cruises themselves offer daily fares that are similar to any in demand peak season cruising.