From a certified Hawaii Snob:

Don't stay in Honolulu it is a waist. It is almost line NYC on the water. You can visit but here's what I would do:
Stay in Turtle Bay, you won't regret it. It has it's own cove great for snorkeling just as good as Hanauma Bay and it doesn't cost anything to swim. Board rentals also avail for Surfing. (Sale now Maybe just got a flier)

Take the H2 out of Pearl to 99 towards Haleiwa.
First Stop: Dole Pineapple Plantation (short trip don't get roped into anything long) on the way to the Hotel.
Second Stop: Hotel. Enjoy the day relaxing there. Hopefully they aren't filming another movie there. Last time I went they were filming MIke and Dave Need Wedding dates and my normally zen/tranquil location was not so quiet.
Day 2: Wake up. Go north on 83 about 10 min drive and go to the Hukilau Caf. This in name is the same that was on 50 first dates but not the same location, still a great dive breakfast place. From there drive to Laie Point. This location was on Forgetting Sarah Marshall (same as hotel) where they jumped in the water, gorgeous 360 views.
Sometime after lunch check out the food trucks you passed.
Giovannis shrimp truck is the most famous but there is plenty there that is awesome we have tried it all. Warning, the Thai food that says spicy means it.
Dinner head down towards the Bonzai pipeline to Haleiwa. We like Haleiwa Joes, or Banzai Sushi. Great shopping in this area or paddle boarding as well. You also have to get the Famous Matsumoto Shaved Ice in this town.
Day 3. Leave early and hike the Waimea Valley. It is awesome and ends at a waterfall you can swim at.
Takes about 1.5 hour round trim all well paved. They have walls with all the movie posters of films that were filmed.
If this is it and your time is over Check out at about 11 and drive around the East side head back down 83 you will pass China mans hat in the water at a nice park and somewhere in that area is Mikes Huli Hut Chicken. It is great.
Take 83 to 72 and keep going around. There are some cool overlooks along with the Blow Hole on this route.
This will put you in Waikiki around 2ish. Still plenty of time before your late flight home to do some touristy things and you are only 15mins from the airport. Park and shop there.
Enjoy!

Edit: If you have an extra day: Relax at the beach then Luau ( I haven't tried Turtle Bays Luau heard it is just ok) Suggest Germaine's Luau. It s a travel over to the SW side of the island. The Polynesian Cult center is great, but it is done by BYU so no alcohol, I go to vacation to drink so that didn't work for me. Best by far Luau is old Lahaiana (Sp?) but that is in Maui.