We were there March 13. We had booked ahead of time to go to the Arizona @ 11:00. Left Aulani 9:20, arrived 9:45. Traffic busy but flowing at that time (Thursday). Normal rush hour is 5am-8am according to the Honolulu travel guide on Wikitravel, so we planned this to limit the time spent on the road, and allow a leisurely start to the day. (It is a vacation, after all!)
We used coupons found in the park's guide to get a discount on the audio guide, before our boat ride. I noticed a couple using a headphone splitter to share an audio guide, which would be cheaper than coupons! We found it good to have the audio guides for the ride to & while at the Arizona Memorial, as someone else mentioned, so recommend getting them upon arrival. They're yours as long as you need them.
Spent some time in the museum beforehand, then more after. (USS Arizona Memorial stamp first day of issue ceremony was that day, as well, so we HAD to get one!)
For lunch, we grabbed sandwiches & drinks at the vending stand, and pic-nicked in the shade around the Visitors Center. Nothing special, but found fresh sandwiches at an OK price for Hawaii, and it made planning the day much easier. Since you cannot bring any bags to the Memorial, packing a lunch along isn't really an option.
The Missouri is accessed by a shuttle bus, terminal is towards the Bowfin. No reservations needed, and you might even want to wait until after you've seen as much of the museum as you can stand before buying your tickets. The same bus loops to the aviation museum, if you're interested in that. There is a decent canteen at the Missouri, so there's another lunch option.
My GPS accurately located the Memorial in the middle of the harbor, which didn't help navigation much. If you find the same problem, the address to use is 99 Arizona Memorial Place, as shown on map below.
