BTW - to add to JTKauai's post.... I was talked out of a convertible by almost every regular poster on this board for my first trip there. I normally love having one in Hawaii and was really grateful they talked me out of it. They saved us the trouble & a decent sum of money.
Too many sporadic "blessings" to keep the top down for any length of time. I'll stick to convertibles on the other islands, but in Kauai I'll stick to a regular car.