Well, first off - if you are diving that cold water - I would only go with a dry suit - you can get a skin or a shorty for the tropicsfor $100 or so - you would not be using a 7 mil wet in FL - trust me!
So I would recommend you go with a dry suit - for one thing - you may think the issue with the water and the wrists/ankles is ok "for now" but really - you are going to get cold, when others do two dives you will want to stop after one...
So - find a good store - I would look for something technical or GUE and start looking at suits - also decide if you are going to set a budget based on how much $$$ you want to spend or if you are going to pay what the best suit cost... the advantage of the drysuit is also that if you are willing to put a couple hundred bucks towards it - you can get custom fit, now you are talking seriously good fitting - including getting boots that actually fit you...
I did what you are proposing - got a wetsuit and figured that I would get a dry suit downt he road - but I regret it - I wish I had put the $300 asides towards the dry suit then and just gotten it sooner...
well, that's just my opinion - find the best suit that you can fit stock - maybe take a look n Ebay - you see some nice suits out there - brand new at reduced prices from time to time...
Let me know if you have more questions,
Dane