I just moved from Big Pine Key, FL last year. The FKCC dive site is only open to the college, so make sure you talk to them before you dive it. It’s not that interesting though unless you’re instructing. In Key West, the dive operation to use is Captain’s Corner, they are they lowest price and have the highest quality. I’ve only used Cpt Hook’s in Marathon, FL and had a pretty good experience with them, though the costs were covered for me so I didn’t pay attention to what they were charging. Looe Key Reef is the best reef in the lower Keys. There are a lot of operations on Big Pine, and Looe Key Dive Center on Ramrod. LKDC gives you 3 tanks per trip, and on Wednesday morning’s they do a wreck.
Hope this helps. Enjoy the Keys