I'm not from Hawaii, but you may want to pick up a good guidebook. We were in Kauai last fall and found a lot of great hikes with the "Ultimate Kauai" book, and I know they make a version of that book for each of the major islands. It's probably worth $15, anyway.

Though I suppose if you're living there you may be able to get a dedicated hiking book with more details. Just a thought.