Hi Jan,
I think Fort Lauderdale is a great choice but I tend to be biased since it is my home
I would not let hurricane season play a role in your decision unless of course you see one coming
In m my opinion hurricane season also happens to be the best time of the year for diving here. We have warm water and calm summer & fall seas except for an occasional hurricane or storm. The water temp will be in the mid to high 70's, we typically still have very good weather in Sept, Oct and Nov. I don't get my wetsuit out until December. In my opinion Octoberish is the best time of the year for diving. The only months that bring alot of wind are Jan, Feb, March & April (April can sometimes be a transition month wind-wise) but even those months offer many good diving days. The vis will vary from say 15 feet to around 100 depending on how close to shore you are. On a calm day I would say the vis is at least 15 feet off the beach unless the previous day was very rough.
This is a great place for wreck diving. Large Ships are very frequently sunk here for creation of artificial reefs. There are several good wrecks right off Lauderdale. I remember reading a statistic somewhere that said Broward County had more wrecks per square foot than anywhere else in the country. Now I can't remember where I read this so I can't vouch for its truthfulness but I will say that there are ALOT of wrecks only a short boat ride away. It may have some truth to it because it gets deep quickly as you head east so the wrecks are densely packed along a thin strip of shallow water within sport & tech diving range.
I would recommend staying close to the beach in Lauderdale by the Sea. If you stay in a hotel along LBTS you can beach dive and/or snorkel with little effort and little expense when you are not on charter boats. In fact, I frequently dive a local wreck launching my kayak right off the beach here. You can walk to local restaurants and bars and the fishing pier near Commercial Blvd. By the way, you are planning your trip during open lobster season and LBTS beach diving is great for lobsters
I rarely go on local charter boats otherwise I would give you a recommendation but I am sure that others here will chime in with some good advice.
Hope this helps