Some of the Sapphire has been updated, some has not. I don't know how to tell which ones have. It has a pool and no beach. You would have to drive about 5 minutes to the beach at Mullet Bay. The waves may be a little rough for a toddler. Parking can be a hassle at the Sapphire. Sapphire is located in an area called Cupocoy (sp?). There are some high end restaurants and a casino there. Cupocoy beach is usually a clothing optional beach.
The Atrium is located closer to the airport. It used to be really nice inside,marble granite etc, I heard it had some issues, may have been taken over by a different management company. It has a calmer beach, with numerous boats moored in the area that you can walk to easily. There are many less high end but still nice restaurants in the area. Some would say it is a more central location.
Hope this helps.