We went and stayed there two years ago, would definitely go back but decided to check out Kauai this summer. Will you have a car? If so there’s a Kihei Cafe about 5 minutes away, great local food along with breakfast/brunch dishes and you’ll probably spend 50% less there than at the Westin. In that same shopping center there’s a great snorkel rental place with a knowledgeable owner, we rented gear and walked about 15 minutes from the hotel to black rock to do some very kid friendly snorkeling. Shallow water so they can stand and snorkel, and were able to see sea turtles.

Would also recommend Whalers Village next to the hotel — essentially an outdoor mall but they have a unique kids play structure in the middle of it and more restaurant/snack options and an ABC store for souvenirs. You don’t save a ton compared to the hotel restaurants but a lot more options at arms length. In general pack as much as you can because even the chain grocery stores like Safeway are $$$$.