A visit to the Arizona Memorial is highly recommended if you are staying more than a day or two in Oahu. The site is exceptional - from the information placards to the layout of the grounds to the movie to the excellent US Park Service Rangers to the Memorial itself. The visit can seem overly regimented with tickets and specific times you can actually go to the Arizona; however in light of the volume of crowds it is understandable.
The memorial to the submarine fleet was eye opening as I do not believe it well known how many submarines were sunk in WWII. Highly recommended.
Logistics : It is possible to negotiate with a taxi for a $70 round trip from Waikiki. This helped save a lot of time and was far cheaper than the meter (>$100). Once at the memorial you collect your ticket to schedule your movie / memorial tour. If your ticket is for 1 to 2 hours after your arrival, you may approach the US Park Ranger once he has let all the people in for a particular movie time and ask if there is space for 1 or 2 others. The answer is usually 'yes', as people book the tour as part of large groups but then are no shows.