I just found this: So, it basically looks like no benefits almost at all. Multiple reports of not being able to use or apply SNA either.

xiii. Autograph CollectionŽ Hotels - all locations except for:

A. Atlantis, Paradise Island, Bahamas participates in the Loyalty Program as follows:

(1) Points or Miles may be earned for reservations booked through www.marriott.com/atlantis, by calling +1 (855) 696-4732, or booked through Atlantis Paradise Vacations, by calling +1 (800) ATLANTIS or +1 (800) 285-2684. Points cannot be redeemed for reservations booked through Atlantis Paradise Vacations. Points or Miles will not be earned and Points cannot be redeemed for reservations booked through AtlantisBahamas.com.

(2) Points or Miles may be earned and Points may be redeemed for stays at The Coral at Atlantis; The Royal at Atlantis; and The Cove at Atlantis. The Reef at Atlantis and The Beach at Atlantis participate as earnings locations only.

(3) Redemption stays at The Coral at Atlantis; The Royal at Atlantis; and The Cove at Atlantis will include a single or double standard room, including the cost of the hotel room, room tax. Extra-person charges for the third, fourth, or more guests in the room is an additional fee and not included in the award redemption as form of payment. This fee as well as all other property charges, including resort fees and service charges are the responsibility of the Loyalty Program Member and are not included in the stay.

(4) Points or Miles may be earned on room rate only.

(5) Limited benefits are provided as described in Section 1.3, Section 3.7, Section 4, except for the breakfast option associated with the Platinum Elite Welcome Gift benefit which is not available, and Section 6.4.