Starwood Preferred Guest - Westin St. John versus Westin Casuarina (Grand Cayman)

I am planning a honeymoon and am considering both the Westin St. John and the Westin Casuarina. Will be using points for 10 nights at least. Have a few questions:
Has anyone experienced both hotels? If so, which would you prefer?
Has anyone used points at either hotel? If so, how was your PLAT upgrade experience at either hotel?
What is life outside either hotel like in terms of snorkeling, sailing, putzing around, restaurants, bars, etc.?
Does the hotel itself have a lot to offer in terms of activities?
Would you reccomend staying at either of these hotels on a honeymoon?
Finally, has anyone had difficulty obtaining a room for points at either hotel (I have plenty of time...I think)?

Your comments are greatly appreciated...

I stayed at the Grand Cayman property using a free weekend and was upgraded to an oceanfront room (platinum). The room was nice but rateher small. The hotel appeared to be the nicest on the island. We took a charter snorkel trip to Stingray city which was wonderful. the island was pretty and clean. There are a number of nice restaurants near Georgetown along the waterfront. The nightlife appeared to be non-existent. Overall, I think it would be a good choice for a honeymoon.

We were upgraded to a Jcuzzi Suite at St. John. Many threads exist on this hotel that can be accessed using the search function.

You should rent a car and explore the very cool island, and you will have a great time.

They are two different properties on different islands. Westin St. John is more spread out, service not so hot, rooms are nice, beach is pretty good, overall good. The island of St. John is incredible for snorkeling, water sports, beaches, some nice shops and restaurants, but quiet at night.

Cayman is a more happening island with very nice beaches but lacks the astounding physical beauty of St. John. However, there are lots of restaurants, shops, and more nightlife. Watersports are excellent, particularly diving. The Cayman Westin is beachfront and you can snorkel right off the beach. Very nice property with helpful staff and good food.

Overall, I like the Cayman Westin more than the St. John property, but prefer St. John the island to Cayman.

Email me if you want to discuss further.