Which tower is pretty much a non issue for most folks. The Ewa Tower is the longer of the two and has more rooms in it. All (or most of) the hotel space is in the other tower, so most of your DVC space will be in the Ewa Tower.
We’ve never done the luau on property because of the price point. A lot of people prefer to go to a luau in Honolulu if they happen to be out at that end of the island for the day.
For me there is no “must do” event at Aulani. Don’t get me wrong, it is the most relaxing place I’ve ever been! There will be daily activities on property (e.g. story telling, movie night, Aunty’s for the kids), and there are rentals on the beach for things like kayaks. But there is no one event that will make or break an Aulani visit.
Biggest issue at Aulani is the food. You have AMA AMA, the upscale restaurant, Makahiki, which is your character breakfast and dinner buffet, and Ulu Cafe, which is quick service. Then you have the pool bar and some kiosks. So there is not a lot of selection. With a 2 BR I’d take a quick trip to Walmart, Super Target, or Costco, all of which are close to the resort. The gift shop has basic DVC sundries and groceries, but it’s all very pricey. You also have a couple of restaurants across the street and an ABC store.
Good news is there is no wrong way to do Aulani.