Sounds like you have some experience and taking steps with your sailing class for more. I would not make any long term plans to save for a catamaran or the like. You might find you do want a catamaran. Only you know when you are ready to own a boat. When you are ready, you should not purchase one larger than 42 or so feet to be able to single hand. And if you find a mate before you find a boat, be careful not to let him talk you into too large or expensive a one. You may part ways and be stuck with too much to handle.
As a fellow boater in Fort Lauderdale, I do not know how satisfying a daysailor will be. Fort Lauderdale is really a storage place for crossing over to the Bahamas. It is tedious to get downriver through all the bridges, and then when you get out the cut, you probably will be in heavy chop. You might have trouble sitting there watching the sunset with a vodka in hand. Biscayne Bay is nicer for that kind of sailing. Fort Lauderdale is a great place for maintanence and hurricane storage and jumping over the Bahamas or even Caribbean.