Blue Heron Bridge is full of fascinating little creatures you would be hard pressed to find out in the open ocean. It's protected from the sea, in some parts you may have snorkelers around, and your average depth might be something like 15 feet. You could very well have a 2-hour dive there. So in some ways it's more like diving in a swimming pool than the ocean. If the goal is to see interesting things, I wholeheartedly recommend it. (And as others have recommended, hire a guide who can spot all these well camouflaged animals.) If your goal is to learn/practice shore diving, maybe do a first dive at BHB as an introduction to the concept, and then head down to Lauderdale By The Sea, as you mentioned. LBTS is the ocean--what I'd call a "real" shore dive. Walk onto the beach, past the sunbathers, and wade into the surf. As it's the ocean, it will get deeper the farther you go out. It will take a bit more concentration, and you need to be sharp. There isn't as much to see--neither loads of animals nor a healthy coral reef--but it can be a great learning experience.