Why such a short stay? How many nights do you have on Maui?
I believe the Hyatt on Maui is a Hyatt Regency, a step down from Grand Hyatt. Is that correct, experts? There is a Grand Hyatt on Kauai that is highly recommended. The Four Seasons is considered the best hotel on Maui, though it's not in Lahaina, but in Wailea.
With teens have you considered a condo or a villa?
Between Hyatt regency and Westin Resort, I think the Hyatt might work out better for you-the rooms at both the Westin and Sheraton are smaller than at the Hyatt-450 sq.ft. v 340 sq.ft. at Sheraton and the Ocean Tower at Westin and 400 sq.ft at the Beach Tower. The Hyatt is a fine luxury hotel, it has undergone some major renovations within the past two yrs.
Well with teens I'd go with a condo...more room to spread out AND that fridge for the eating machines. Look at the Whaler, Kaanapali Ali'i and the Marriott Beach Club right on Kaanapali Beach...a little north are the Honua Kai and Westin Kaanapali Ocean Resort Villas, these are condo/tels with full resort amenities as well as the Aston Kaanapali VillasKaanapali Villas.
The last three are on the quieter side of Black Rock but still with easy access to Whaler's.
I've stayed at both the Westin and the Hyatt and prefer the Hyatt. The rooms are larger and nicer and doesn't have as much traffic on the walkways near the hotel.
It's not a Grand Hyatt, just a Hyatt. The Grand Hyatt is in Kauai.