Renting a car has become quite pricey in Hawaii, however now there is a new option that is affordable, gives you access to many different options and the best alternative to renting from a traditional car rental company- TURO!
Below we also have some other links to better options, including TURO (the airbnb of car rentals) which have recently become a great alternative to renting from a bigger company.
If you are going to any other island besides Oahu, I highly recommend getting a car. Its the best way to see the entire island and most points of interest are clearly marked and easily accessible by car. The bus systems on the other islands are mostly meant for locals going to work, so they do not run often and its not a very convenient way to get around. Simply put, you spent a lot of money to get to Hawaii, don't miss out on seeing the islands by wanting to save money and not renting a car.
With regards to Oahu, the bus systems are great for getting to specific points, but be aware that you will be spending a lot of time on the bus as it makes frequent stops. For example, if you want to go to Pearl Harbor & Arizona Memorial, that's at least a 1.5 hour bus ride. Renting a car, in lieu of doing a circle island tour is the best way to get around to seeing multiple points of interest.
Recently, there is another transportation option which is great for visitors and locals alike as an alternative to renting a car, using the bus, a shuttle, taxi or taking a tour; Uber & Lyft. These simple apps will take you to places around the island for really cheap compared to the other options of shuttles (which charge per passenger) or taxis, which charge an arm and a leg. For example, an Uber ride to the airport from Waikiki is around $18. You can even take a Lyft ride from the airport to Waikiki for around the same price, which is way cheaper than taking a taxi, which is around $45.
Below are PROMO links to UBER and LYFT that you can use if you don't have these apps yet and get FREE & DISCOUNTED RIDES!