Aloha,
Just back from our second family trip to Aulani - everyone had a great time! One week was about right ( but as west coasters we have been to Oahu and Maui many times).
We had a ground floor one bedroom with pool view (can't remember tower name but it was on spa side). Loved the ground floor and this tower as it provided easy access to pools, beach, Ulu café, beverage station, gym, parking area etc. We found we simply did more as it was so easy to go back and forth from room.
The resort itself is truly incredible. The lighting at night is beautiful. Loved the morning and evening swims in ocean, lazy river in evening and infinity pool and hot tub. My favorite still is the adult quiet pool - one of the most shaded areas and very relaxing. Staff are awesome - very helpful and friendly. Ko olina beach area provides nice area to walk (or jog) along the beach walk that connects the 4 lagoons. We made it a habit to watch the sunset each evening - beautiful. Loved the mornings having coffee in front of Ama Ama.
Although apparently it was at near capacity, we didn't find the beach / pool chair scarcity thing to be a huge issue. We could always find chairs. Of course some of the top locations (based on view / shade) are staked out pretty early.
We had only two slight negatives which were not big deals. First, there were quite a few guests who seemed to like to skype or face time in an extremely loud manner and for extended periods of time - most seemed to be doing work with mainland. The other was that they are doing a pretty major reno next door at the Four Seasons. While we were there they were doing lots of outside work with excavators and jack hammers (yes, jack hammers for good part of each work day). It was noticeable but not pre-occupying.
Ulu café was surprising good and we loved Ama Ama breakfasts. Went to both Monkey Pod and Roy's happy hours - both good. If I had to pick, I'd go with Roy's. Went to many good restaurants and food trucks around the Island. They included Dat Cajun guy, Ray's Huli Huli chicken, Teddy's bigger burgers, Steak Shack, Ono Steak and Shrimp, Surfn' Salsa, and a great udon place and a pork cutlet place in Waikiki. We got lots of fresh poke from different locations and some great musubi. Of course we had to get some malasadas at Leonard's truck. We have had a lot of shave ice over the years and the Aulani versions are very good. Make sure you ask for a blender - we made lots of pineapple / iced mixed drinks in our room. Overall, we had a great variety of affordable and good food.
IMO, a car is a must if you stay a week or longer. We are
DVC members so we don't have to worry about the $35 a day parking ( I have to admit I wouldn't be happy paying this). As others have said, traffic can be bad so plan to avoid rush hours and check for road work.
We love the North Shore and in particular swimming at Waimea Bay. We had great time jumping off the big rock into crystal clear blue water. Young and old alike climb the rock and take the plunge. We also love Kailua and Lanikai Beach area. We finally did the pill box hike at Lanikai which was a lot of fun with some great views. We snorkeled at nearby Electric beach. Unfortunately, the waves were rather large the day we went which made conditions challenging (very difficult entry, poor visibility etc.). I would only recommend trying this spot if you are VERY strong swimmers - not for younger kids IMO (I have only been the once so maybe it is less dangerous in calmer conditions but be cautious).
We went to Waikiki twice - ala moana mall, some restaurants, and catamaran cruise. Although the beach is nice and there are some great restaurants, I am no longer a big fan of Waikiki. It is a lot of concrete, it is hot and it is crowded.
Overall we had an excellent family vacation - something for all ages at a location that can't be beat. I am sure we'll be back.