Hawaii has a very rugged, mountainous terrain that is spectacular too; for those visiting the islands, a helicopter ride could be the best way to get to see them quickly and without too much effort.
A ride in a helicopter is not a very cheap way to travel; it is more expensive that an airplane and there are not many helicopters around. But in Hawaii you will find a number of companies that will do the work for you. Then, you should consider that for most people, except for those true adventurers that have the skill and knowledge to traverse jungle and mountains, the choice is either a helicopter or nothing to see.
The mountains in the archipelago are high, valleys are deep and their wall are almost vertical, carpeted with vegetation. It is not an easy place to do some casual trekking. But there are lots of places that have beautiful landscapes, panoramas and scenarios, and it would be a pity to waste the opportunity to see them.
In other words, it seems to me that despite the price, taking a ride in a helicopter there makes a lot of sense because travelling all the way to the middle of the Pacific ocean just to stay limited by terrain and money seems nonsensical. Think about it: Your trip there could be the only in your life, so there is no time to lose. If you have children, going up in a helicopter to fly around such a spectacular scenario would be a memory of a lifetime; they will certainly enjoy the ride, plus, if you are keen on photography it will provide you with unique chances to make superb pictures. You will find some of such services that work organising helicopter excursions at the islands here. Enjoy!