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You can get some amazing ocean-front views (if you pay for them) on many islands. Make sure you book ocean-front, and not ocean-view rooms. I'd recommend that you speak to front-desk personnel who are familiar with the properties to maximize you chances of picking an appropriate room category.

Some favorites:

Oahu-
Four Seasons Ko'olina
The Kahala Hotel
Nothing in Waikiki except ultra-expensive rooms at the Halekulani.

Big Island-
Hapuna
Mauna Kea Beach Hotel

Lanai-
Manele Bay

Maui-
Even though the Grand Wailea is on the beach it is a very large property...
Haven't stayed there, but people like the Four Seasons Wailea and Anduz...

Good luck!