Mass transit in S. Florida sucks. There is a little metromover/train route in Miami, but that's downtown and not near the beach. The main way to get around is by car. Rental cars generally are cheaper than taking the taxis unless you are staying on the beachfront. There are some shuttles along the beachfront that do little loops, but again, you need to be staying there. A lot of people's condos are pretty far away from the beach. And everything is spread out, so between Ft. Lauderdale and Miami is about 30 miles. There's a lot of reefs and wrecks all up and down the coast. But if you go out on a dive boat, they tend to go to a few specific spots, so even if you were to ask here and get some recommendations, they may not want to take you there.
Most of the bigger wrecks are AOW, because they try to keep the shallowest portion deeper than about 60 ft.
If you're coming this time of year, do the morning dives. Afternoons tend to be rougher with more chance of rain/storms. And watch the weather, there's a lot of stuff going on at this time of year that makes the seas rough.