There are numerous offshore wrecks that people like to dive, and the numbers are published. You can either go to the Florida Wildlife Commission web site, or Floridasportsman.com, and follow the links to the numbers.
I am not a charter captain, but I do have a Venture 34 with twin 250 yammies, and go out frequently with friends. We like to spearfish a dive or two (just enough for the dinner table that night), and then shoot photos. We dive ledges and wrecks anywhere from 40 feet, all the way out to the Florida Middle Grounds, which ranges from 90 to 130 feet. I am now just in the process of doing my deepwater training, so have not personally dived the Grounds yet.
By the way, the spearfishing we do is over hardbottom or ledges I have found on my own. I have not taken fish off the popular dive reefs.
Sharks are rarely spotted, although I read a post from a guy diving recently that had a bull shark come up to him to investigate a cobia he had on his stringer.
Good luck with your trip.