The SCUBA at CTI is fairly good. For the resort course, the dive is ~30 feet, and most of the time it takes place over the reef directly off the coast in front of the resort. You can still see the dive boat in the afternoon while they are out there.
For the daily certified dives, they have several locations, ranging from a 30-40 foot wreck, to a 80-90 foot wall dive. There are several reef dives all ranging in depth, but nothing deeper that the wall dive.
Wildlife: short list of significant sightings - Nurse Shark, Barracuda, Dolphin, Turtles, various reef fish, Lobster, Conch, and during a night dive, tons of shrimp, urchins and even more lobster.
If they have room, there should not be an issue joining your wife on the resort dive in the afternoons.
E. Lee Cunningham
Social Technologist, GE