4. Especially, if you've never explored Oahu, you owe it to yourself to get to North Shore to see the beautiful beaches, huge surf (during the winter) or great snorkeling (during summer), eat Shave Ice, etc. Also, with a car and good guidebook or the Internet, you can find more 'local' places that non-tourists frequent, which will give you a better sense of the real Hawaii, not to mention save you money.