Following the suggestions of the group, I took the Stingray City dive. As some of you guessed, the first dive was the North Wall. Amazing!
I booked the dive through the cruise ship and found it almost the opposite of what people say about cruise dives. This one was an 'Advanced' dive. We went to 110' (my max so far) for the wall (12' for the Rays). When I got to the meeting place for the excursion, it was swarming with people. Fortunately they had several dives scheduled and informed us that we weren't all on the same boat. Don't know how many boats there were all together. By the time we got to our busses I found that there were only 3 of us going on my dive. We had the whole boat to ourselves. Also, the DM wasn't too conservative and didn't cut the dive short, although she did monitor everyone's levels fairly well.
The dive lasted 40 minutes and I couldn't have stayed any longer. I notified her when I hit 500#. I hit the boat with 350lbs in the tank. We snorkeled back to the boat so that we wouldn't completely drain the tanks. One of the other divers was a confirmed air guzzler and brought his own extra air. He said that he does that as a courtesy to other divers so that he isn't the reason that we have to come up too soon. He sucked both tanks dry.
Stingray City was certainly an experience. I'm glad I did it, although I would agree with the folks here that I don't need to go again. If I get back to GC I would do the wall again though. Awesome. I've seen nothing like the view as you cross over the edge and look into the limitless deep blue nothing.
I have to admit that my air consumption has improved tremendously. I dove 3 times on my trip and was never the first to run low. Most dives ended by meeting the predetermined time limit. One ended when the DM hit 500 lbs, I still had 1100.
Managed diving in Ft. Lauderdale before the cruise, GC, and Cozumel during. GC was the best.
Thanks for your suggestions, they really helped my vacation.
Dave