I've heard good reviews of the Paradise Cove luau, that it's nice and the convenience to Aulani makes it worth it.
Without knowing anything else about your trip, I suggest you rent a car for the whole day so you can see other locations around the island and end the day with the Toa Luau. There are lots of free locations around the island worth seeing.
For other meals, the Foodland Kapolei delivers to Aulani, and they have a large menu in addition to normal groceries.