Quite frankly it's impossible to see everything on a cruise. Just not in port long enough.
My wife and I cruised to Hawaii last April, 2000 from Ensenada aboard Rhapsody of the Seas. We were only able to sample the offerings there. Thus, we are going back on Infinity this year. However; we still, after two cruises, will not have seen everything.
The best thing you can do is to get some travel guides and use the internet to surf for Hawaii. One good site is gohawaii.com. Go Hawaii is a newsletter on the internet that is written by the local Hawaiians.
For your first trip, I'd recommend (1) seeing Kilauea Volcano. That's on the Big Island of Hawaii and usually is offered while in Hilo. (2) Do an adventure tour while in Kona. We went to the Valley Falls Water Fall. It's considered an adventure excursion because you go into the back country and hike to the falls. (3) In Maui, I'd recommend the bike ride down the volcano and (4) the second day walk the town Lahaina. In Kawai (5) go for the movie tour, you'll probably need to make arrangements yourself as some ship excursions don't offer this. In Oahu go to the (6) Polynesian Cultural Center. You'll be better off (if you're doing a Post Cruise Package) to make the arrangements yourself. If you can spare the money go for the Ambassador Package. It's worth it. Somewhere in all of this you should work in snorkeling.
These are just suggestions. There's a lot more than this and all, in one variety or the other, equally good. Make a long list and then narrow it down.