Direct flights from California to Honolulu are generally easy to find and around $300-500 round-trip per person. Hawaiian Airlines, Delta, and Alaska Air have the most routes and best pricing. No need to fly to another island, most flights can be booked direct to HNL (airport code) on Oahu.
The Honolulu airport is approximately one hour from Haleiwa, the North Shore, and recommended accommodations. The only place to rent a car on the island is near the airport. We highly recommend that you make arrangements to rent a car or split this expense with your party, as it will provide you with the maximum freedom needed to explore the island. If you are looking to Uber from the airport to the North Shore, we suggest you stay in the town of Haleiwa so that you can get around by foot, Aloha Bus, or hitch a ride with friends. There are no taxis and very few Uber once you get into the country. Renting a car is the best option for getting around in a timely manner and traveling to other areas of the island, such as Waikiki or Kailua.