Getting Here and Around
Unless you plan to stay strictly at a resort or do all of your sightseeing as part of guided tours, you'll need a rental car. There is bus service on the island, but the bumpy buses tend to run limited hours.
You most likely won't need a four-wheel-drive vehicle anywhere on the island, so save yourself the money. And although convertibles look like fun, the frequent, intermittent rain showers and intense tropical sun make hardtops a better (and cheaper) choice.
If possible, avoid the "rush" hours when the local workers go to and from their jobs. Kauai has some of the highest gas prices in the Islands.