jkjetsetters

I saw that you also posted on the 26th in the Westin Maui thread that you were trying to decide between it & the Hyatt Regency, so it sounds like maybe you've narrowed it down to those two. I've stayed at the Hyatt Regency, Westin Villas, & Westin Maui, and they all have their pros & cons. I'll start by saying that I do generally agree with @travelinmanS, both the Hyatt Regency & the Westin Maui are mid-level, family friendly hotels on Kaanapali beach with similar offerings, so I would probably do whichever one is the best points deal. But, let me add a few more thoughts.

The Westin is a lovely, tropical property, on a nicer stretch of beach, right next door to Whaler's Village (lots of shops & restaurants), and one tower of the rooms (Ocean Tower, I believe) were nicely renovated in 2014. It has an adults only pool & bar, & a huge main pool that's also very nice with a large waterslide. They also provide a shuttle to the Westin Villas & the Sheraton (in case you want to go eat at one of their restaurants) & to 3 different stops in Lahaina, which is nice. The on-site dining is nothing special, but again, you have Whaler's Village next door which adds several options. The Westin Spa was nice, we had a lovely couples massage there and enjoyed the facilities. I haven't been to the Hyatt spa though to compare.

The Hyatt is a beautiful property with a gorgeous, huge pool overlooking the ocean. The Regency itself doesn't have an adults only pool, but the main pool is so large that it's easy to find space to get away from kids if you want, and they also have a great 'keiki lagoon' pool where many younger children play. Additionally, now that the Hyatt Residence Club is open next door, you can use all 4 of their pools (and other amenities), including an adults only infinity pool. Back at the Regency, something else I'm sure your young adult children will love is the swim-through waterfalls & cave & the grotto bar inside, it's really fun. The pools are also open an hour later (til 11pm) at the Hyatt vs the Westin, if you have any night owls.

I think the Hyatt has better food options, if you ever eat onsite. They have more restaurants onsite than the Westin period, and I think better quality/nicer. Japengo is one of our favorite restaurants on Maui, and we have eaten at many nice/highly praised places. It's delicious, and has great views. Additionally, Umalu is open until midnight which is nice. The beach is not the greatest, but it's a short walk up to nicer stretches of beach. Unfortunately the Hyatt only provides a shuttle to Whaler's Village, so Westin does have them beat shuttle-wise. The rooms also haven't been fully renovated since 2011, though they're still pretty nice. Oh, I can't forget the Penguins in the lobby of the Hyatt, one of my favorite things there!

Will you have status with either SPG or Hyatt? I would factor that in as well, since that could get you some nice benefits like free breakfast in a lounge, discounted parking, etc.

Let me know if you have any questions!