We live in CT, just over the border and use LGA and JFK all the time. I prefer LaGuardia generally, it's a bit closer and the Long Term Parking is quite closer to the Terminal than at JFK. But I think JetBlue only flys to Ft.Lauderdale from LGA. I have never used JetBlue from there, only from JFK.
At JFK long term parking is cheaper, but you take a monorail shuttle to the JetBlue terminal. This process takes a while, I would leave almost an hour or so for the transfers. I find it to be pretty easy overall, but the extra time/schlepping of bags is a hassle. The JetBlue terminal though, is a dream. There was NO lines anywhere, plenty of places to hang out while waiting for the flights, and friendly FA's.
If the price is right, I would say go for it! Just plan on some extra time transferring to the terminal.
Good Luck,
cortegro