HiloSunshine

You can catch the county bus across the street from the pier at the Keaukaha Market. The cost is $2 per person and it will take you to the bus terminal which is located across from the Farmers Market. Be aware that the bus doesn't run on Sundays and Holidays. You may check out the bus schedule at http://www.heleonbus.org/schedules-and-maps (The route you need to click on is the "Intra Hilo Keaukaha"

I don't know about other islands but in Hilo, you head off the ship and there are some tour operators standing in front of the Aloha Room. They are only allowed in two at a time and only for 20 minutes. They aren't allowed to hold "tour" signs because of solicitation rules at the pier but easy to spot because their vans are their advertisement. But there are taxi drivers that are allowed to hold up "tour" signs and your charge will be metered. I've heard horror stories about them from cruise guests so I'd be skeptical. Mary Lou's is excellent, Gecko Tours and C Big Island have great feedback also. Go to TripAdvisor for their reviews.

Polynesian Adventures is owned by Norwegian Cruise Lines. If you want a bus tour, I'd go with Roberts Hawaii. If you want a helicopter flight, make sure you book it far in advance. The cruise ship usually has blocks on most of the seats. Van tours are usually more expensive ranging from a low of $50 to a high of $85. Usually the later times will be cheaper as the operators are trying to fill seats.