I'm going to preface my recommendation with this comment, which some may find objectionable... I have been diving GC 1977. All of which was centered on the West end. In the 80's I discovered the East end, Little Cayman and Cayman Brac. Over the years of comparing the quality of the water, dives and structure, the GC West end has suffered some depredation and became over-run with boats, ships and people. That said, It is the least expensive of the 3. So if you can't dive the cays on your dollar, your best bet to dive the quality of the cays rests with the East End. The prevailing currents keep the water crystal clear and bring bigger critters. Anything that goes into the water on the West End, stays in the water. It is best to stay East, which requires a rental car, you will be driving on the "wrong" side of the road and there are excellent dive ops there. The wall is close to the shore starting at the lighthouse where Ocean and Divetech operate and runs that way pretty much all around the East end. Shore diving is doable. Wind will shut you down though, so weather becomes a constraint and can chase you around the island. Having a car makes you mobile and you can always find a place to dive. The caymans are probably the most expensive place in the Caribbean to buy a sammich, so it would behoove you to stock up at the the market before leaving the West end.