Check out the excursions on Aulani's website. I highly recommend the Disney Excursions as Disney is very well represented with these excursions. I know $$$ may be a factor but here are my top 5 excursions recommendations. I tried to list them in the order I would do again if I had to choose...
1) Disney Excursion Kualoa Ranch Experience - an all day excursion to the north shore with a stop at the pineapple plantation (I think), a boat ride to a private island (where they filmed 50 First Dates), private BBQ dinner & play at the private island, horseback ride where they filmed Godzilla, Lost, Jurassic Park, Journey 2, etc. and you have your own Disney guide that is very friendly and accommodating. I have done this excursion twice. Once with just my DH & I then another time with me, DH, DS(9), DD(9), DD(2.5), mom, dad, & nephew(14). Our Disney Guide took my youngest daughter and my dad on the trolley tour of the ranch since she couldn't ride the horse and my dad didn't care to be on the horse lol.
2) Polynesian Cultural Center with Super Ambassador Package (believe only available on Wednesday)- Expect a VERY VERY long day but very well worth it!!! Includes transportation, stop at pineapple plantation for lunch, ambassador guided tour of each island area with lots of knowledge from your tour guide, luau or buffet for dinner, & an amazing fire show presentation with a ticket for FREE Hawaiian Delight (WONDERFUL) during intermission. It will be late getting home so I always fall asleep on the bus ride home. I have done this twice. My DH & I did the buffet but we did the luau with all the family.
3) Pearl Harbor (Tour 66K) at 8:30am - This one includes the USS Missouri, USS Arizona, the Memorial, Movie, & Punchbowl. Great tours and great history! You are fairly rushed when at Pearl Harbor to go to the memorial and the movie so keep that in mind. I have done this twice.
4) Catamaran Experience: Look for whales (seasonally) and dolphins, go snorkeling and enjoy musical entertainment while you sail along picturesque ocean waters. The crew was awesome! Very supportive & great communication. Good buffet deli lunch. Big boat. The crew took my 2.5 year old daughter snorkeling with them. She loved it until she got cold so they took her straight to the boat and brought her a seastar from the bottom of the ocean. She got to hold it and look at it and toss it back in the ocean when they got done with their 2nd snorkel trip. You are allowed to stay on the boat if you do not want to snorkel.
5) Manoa Valley Rainforest & Bamboo Forest Hike: Behold natural splendor on this privately guided hike through a lush Hawaiian rainforest. You may even see a 200-foot waterfall! The waterfall was dried up pretty much & just a trickle when we went but the hike was very nice. Just don't recommend if you are scared of bugs & insects or don't like hiking lol. Disney guide is very good.
ENJOY!