I loved Hawaii but would not want to live there. I visited Oahu with my hiking buddy in summer of 2006 and saw the entire island except for the south shore. My favorite activities there were practicing yoga on a beautiful beach, snorkeling with turtles and hiking a couple of amazing trails. We were meant to go hiking/kayaking in Kaui for 2 days but my trip was cut short so I had to leave early and didn't get to go to Kaui. I hear it's beautiful.
We visited Maui summer of 2009 and saw most of the island. My favorite activities there were riding a harley from Lahaina to Hana (this ride is legendary but to do it on a harley was incredible). We went past Hana and hiked through a bamboo forest to some cool waterfalls, then on the way back we checked out a lava tube, the black sand beach, and stopped for dinner in Paia (best fish tacos on the island).
We also did some snorkeling in Molokini crater, Honolua bay and La Perouse bay. We drove up to Haleakala volcano, hiked/swan around the acid warzone, had shaved ice at Lorraine's, went to a Luau, spent a day sight seeing in Lahaina, and had dinner at Pacifico which was amazing. Loved Maui but would not want to live there (everything is insanely expensive there).
I didn't think this year's trip to Oregon/Washington could be better than that but it was pretty amazing. When are you going?