Hello dawnv8, welcome to our forum! Sorry to hear about your terrible experience not having the right documents. Did you ever get compensated for not being able to board the ship? I hope you did.
I think you're right about Cozumel being the best port for snorkeling. You might want to do a little research on Chankanaab park. Your going to be in AWE when you board the Allure. My wife and I were on board the Allure last February and were totally in awe. We've been on about 70 Royal Caribbean cruises and we felt almost as it was our first cruise. It took us 3 days to find our way around. We're going on the Oasis in a week and we're really looking forward to it. There will be a lot of members responding to your post - I'm sure all of your questions will be answered.