More about Hawai'i, where I used to go every winter.
Even around Honolulu, much is unknown to tourists.
O'ahu- rental car at airport. But within Honolulu, use the bus.
-Nice short walk, through a kukui and bamboo forest to Manoa waterfall. Drive to start of trail or take Bus 6. (The bus passes Univ. Hawaii, with excellent bookstore)
-Circle Island- take Bus 55. Follows east coast to north tip of O'ahu. A stop at the big hotel at Turtle Bay, good for lunch. One can use the beach below the hotel, or walk SE from there to secluded spots. Get on The Bus again and return through the central part of the Island. A half-day trip, but fare same as local city fares.
Pali- may be some tourists, but the lookout is breath-taking. May have rain there but sun on the beach.
-Many walks from valley heads.

Look at koa 'ukuleles and guitars-
Wahiawa town. http://www.koolauukulele.com
Honolulu. Kamaka. Several types of 'ukes, including 6-string, 8-string, and the guitar-like baritone. Beautiful! http://www.kamakahawaii.com.