I definitely think you're on the right track. I have not used Island Marketing, so cannot comment on their tours. The dolphins, just be sure you book the swim and not the experience. The swim you actually get to swim and be pulled by the dolphin. The experience you do not. It is a truly amazing experience, one that I will never forget. They are so powerful, yet so gentle. Incredibly intelligent and definitely a must do. I'd highly recommend a helicopter tour, if they offer one, for Kauai or Maui. Since you've booked the Luau on Maui, maybe check into the helicopter in Kauai. They are both such picturesque islands.
The Arizona is definitely worth the time. The tour we took offered the Arizona and the Punch bowl plus the government house and Hanauma Bay. We didn't have enough time at Hanauma for me, so went back at a later time and spent the full day there.
Be sure to get some Kona coffee while you're there. Wiamea Falls are beautiful, too.