My wife and I spent a week @ the Marriott on 7-mile beach. Wonderful island with excellent hospitality. Sting Ray City is very crowded and we opted to take a tour with Red Sail Sports for a snorkel trip to a less congested area. We saw huge sting rays, fed them, etc...
Just remember this: the male sting rays are small...the female's will have a wingspan of 6 feet!!