I wonder if we overlapped as we were in 1089, the double room two over from you until the 21st. I had a balcony straight over the ocean, which for the most part was really nice (It was very hot in the late afternoon). I didn't really have any platinum issues since this was the room that I paid for (as far as I was concerned, this was the best non-suite in the hotel) and there were no suites available in the Beach tower.
There have been mixed reviews of this hotel, so here is a synopsis of my experience with the caveat that as the previous poster noted, the hotel was not full, which certainly has led to some of the reputational issues.
Room: Again, I paid for a Luxury OceanFront room, so the only real issue was the height of the floor rather than any other variability. This was a two double bed room (as requested). It attaches to the large suite in XX88. I didn't hear a peep from my room neighbors the entire time, which either indicates a solid build or quiet neighbors. The room and the bathroom were pretty standard Westin stuff. Only real issue was that there wasn't quite enough drawer space for my team.
Food: We ate breakfast at the hotel every morning we were here. It's a buffet. As a platinum, we were to receive free continental breakfast, which is delivered to your table rather than being a subset of the buffet. You have the choice of either sitting landside near the buffet next to the pool or sitting oceanside. As a Platinum, you can opt in for the full buffet, which was $10 per person. We thought that for Hawaii prices, it was an OK deal and the buffet was quite good. We did eat at their bar one evening. The portions were a little small, but service was ultra-quick.
Three of the nights we were there we ate at the restaurants next door to the Westin in Whalers village. Both were solid for us and our kids.
Bar: I went to the bar a few times during the days at the pool as poolside service was somewhat slow. Only thing I would say (and my sample size is low) is that the adult pool bar drinks had a little more kick to them than the standard bar.
Pool: My kids 8/10 loved the pool slide. We did get there pretty early in order to score seats that had shade as well as a view of the bottom of the slide. On a few of the afternoons, there would be quite a few chairs reserved and those people often wouldn't show up. Only one time did I see the staff tagging the chairs to eliminate squatters. Again, I can see how this would be a more fierce issue with higher occupancy. On the second to last day, the pool seemed to receive a heathy chlorine infusion, which bothered my kids' skin a bit, but we have seen this elsewhere (Westin Kierland).
Beach: The beach is really nice in front of the hotel, but the potential undertow and shore breaking waves made it less relaxing for parents with kids. I can see how I would have a nicer beach experience if I nabbed one of the cabanas or umbrellas as a couple rather than a couple with kids. It was very windy for a few of the afternoons and being pelted with sand might mitigate some of the pleasantness. Only real issue I had was with the umbrella rentals. They are $37/day, regardless of when you begin to use them. It would seem more sensible that if one was open and it was the afternoon, that there would be an adjustment to the cost (as there was for the cabanas, which also had a Plat discount).
Luau: We didn't do the Westin Luau as we tried to book too late. It gets good reviews. We did the Old Lahaina Luau, which was similarly priced and just down the road (10 min car ride max). I would suspect that the Westin Luau food was better since it couldn't have been worse than at the Old Lahaina. The only potentially redeeming part of the meal was the pork...the rest was bad. The show was great and our server was fantastic. We couldn't really see well from our seats, so he set up a separate location for us to view the stage and put our kids up front.
Activities: We did a Molokai snorkeling trip and the Atlantis submarine. We booked through the hotel, which was massive rookie mistake on my part (even though I knew better). It cost me likely 25 to 30 percent more for the convenience of not having to click on some things on a website. Both trips suggested by concierge were great, though the Molokai snorkeling experience did not involve as much sealife as I would have liked. The boatride and the staff really made the trip worthwhile.
Don't know what else to add from here...