I live in Hawaii and been to Naples multiple times when the grandparents lived right near there. Florida is hot, it seems much hotter than Hawaii.
As stated, have a job lined up or be prepared for doing some small job.
As far as racism goes, I have not experienced it, and I am white. I lived in Kona (on the Big Island) most of my 8 years here and that is much more local than Oahu. Thing about Oahu is that its busy, and I could see how people could perceive others being racist by being rude. Sure there are some rude local guys around, especially at some of the surf spots, thing I have found though, is if you are nice and respectful no one will give you crap. If someone does give you crap, it does pay to show some backbone, enough to not get hurt but if you ever want to go back their, you can't just sulk away. It does help to have local friends, because locals throw the best parties.

The property values on all the islands seem to be insane. In just 4 years my house in Kona has doubled in value, and up north Big Island, think boonies, the same applies, houses are going for upward of $200k for little tiny places, it is crazy.
I live in Honolulu now and goto UH-Manoa, and Oahu is definatly the big city. Lots of things to . Each island has its own unique feel and flavor. The Big Island is much more relaxed, very spread out, and unless you like nature, hiking, go beach, ocean, you are probably out of luck. Maui is very tourist oriented, and gives the feeling, to me at least, that it is what people think of Hawaii, palm trees on the beach with a hotel and golf course right there.