There are a number of towncar services - two of which have been mentioned here. I've used Happy Limo for my son and his family and they were great. Even adjusted the pickup time because their flight was delayed along the way (my son didn't even have to call them). There's also Mears motorcoach.
With the towncar option, you will be the only one(s) in the car. It'll be a straight airport to Dolphin run (unless you want to make a 30 minute grocery stop). With Mears, you will have multiple stops to let others off and no option of a grocery stop.
Towncars are more expensive than Mears.
Then there is a cab option but that's even more expensive.