A lot of the best of Cayman is deeper than that. At some sites the mooring is at 60'. Once you're certified, typically the first
morning boat dives go deep down the wall to maybe 90+ then they do a shallower second dive. Most of GC is surrounded by deeper walls so that's what divers go there for. So you might find a smaller operator who can pick sites good for both you and other guests after your check-out dives. They do exist - even some of the best of the pinnacle dives start very shallow - like 20-30' or less. You would just stay on top instead of dropping down and working your way back up. They will always put a DM in the water with you - it's the law. With some of the smaller operators - many take 6-8 divers max. you'll have more influence in where they go. Or dive with some of the Georgetown operators - they're used to cruise divers and new divers. There can be more people on some of those boats though.
Afternoon dives are when they do the certifications/check-out dives so those will be shallower. A site like Aquarium is only about 45-50' for the best stuff - and it's pretty good - lots of fish life. We even found a couple cleaning stations - if you held out your hand the shrimp would trim your cuticles. Also after certification you would qualify to dive the upper decks of the Kittiwake - a dive prepared wreck they put down a few years ago. And of course there's the Stingray City dive - must do. Only 14' deep but a lot of fun.
Turtle Reef is a really good, really easy entry shore dive. Mini-wall dive just off the dive dock - good stairs down also. At the bottom of the wall it's about 50' to the sand, the other end goes to about 70ish. Big schools of tarpon rest in the shadows there, obviously there's always turtles and we've seen groups of Eagle Rays go flying over. If your wife wanted, she could either visit the Tortuga Rum Cake factory or the Turtle Farm nearby - two of GC's tourist attractions. Turtle Reef also has both Cracked Conch - nice patio dining - and the Macabuca Tiki Bar onsite.
There's also dives near there at Lighthouse Pt. and Cobalt Coast - both start very shallow as well. And downtown is Eden Rock and Devils Grotto - nothing there exceeds 40' I actually thought some of the best reef at Eden Rock was under 20' lots of light promotes lots of coral growth. It is right downtown though near the cruise port so some of it is a little tired.
And Sunset House slightly farther south also has several easy entry shore dives. The "mermaid" is at 55' to the base and there's a lot of shallower reef there as well. Salt Water Pool there makes that a really easy entry. If you're in the right place at the right time, you can watch the tourist sub go by. Even the "wreck" out there is only about 70'. It's a divers place also, My Bar there has good food and is waterfront.
Another option might be Curacao. We did about 20+ dives there and only twice broke 60' - once to look at a wreck and once looking for something we never found. And had a lot of excellent dives. It's shore diving there - except there are many boat operators as well. One advantage Curacao has is it's rare for the water to be much other than flat calm. So getting on/off the boats is much easier for new divers. And it's so clear there you won't lose sight of anyone - visibility exceeds 100' in many cases. We've actually hung on the surface, looked down, spotted some feature and dove down to it.
Almost all the shore dives are beach entries - if needed there's also dive docks. And there's a lot of them - about 50. One of the signature dives on Curacao is the Tugboat - I believe it's at 17'. There's also a pier nearby you can dive under if there's no ship tied up. It's shallow too, maybe 40' to the bottom? The best dive on the other end of the island IMO is Playa Kalki - I know we never exceeded 60' there. Some of the Curacao sites are off small coves and near the far end they're about 40' - then you can go deeper out to the reef wall and drop down as you like. Or not. We stayed along the top of the wall once and found all sorts of eels - more than we had by diving deeper at the same site.
Curacao also has plenty of non-dive things to do for your wife - much more than Grand Cayman. Downtown Grand Cayman with 4-5 cruise ships in port is frankly a hassle. Curacao gets them also but not as many. One other advantage if your wife likes the beach is that there's at least a dozen Curacao beaches that are also dive sites. Nice beaches, shade, showers, every one has at least a snack shop - several have restaurants and just about every one also has it's own on-site dive operator. You could make arrangements at most for escorted shore dives. There's also dive guides on Curacao -
Bas Harts is one - he'll meet you at dive sites and take you diving. The
Dive Bus - that's all they do. Pick you up at any property in town and take you on 2 escorted shore dives.
www.curacao.com
If your shop suggests Bonaire instead, I suggest you save it for later. Entries there are much more difficult than Curacao - typically over ironshore and coral rubble at the waterline. Curacao and Bonaire are 50miles apart on the same reef so have the same fish. Curacao has a lot more non-dive stuff for your wife and you should find it easier to get to also. Compare the site entry photos here for an idea:
http://www.shorediving.com/Earth/ABC/index.htm
