We're looking at coming down at the end of June via STT.
In previous trips we've either flown to EIS or American from Miami to STT. however the prices on Spirit from Lauderdale are $500 cheaper for the 2 of us for our dates.
My concern is to miss the last ferry to RT.
How often does that happen ?
what would be a good plan B if we did miss it ?
Thanks

Be warned, Spirit is the Walmart of airlines. And their sneaky baggage fees are pricey, unless you're just taking a small personal item.

Spirit is just fine, flown that leg many times, nothing sneaky. Their rules and charges are clearly stated on their website. We always upgrade to the "Big "Front Seat", a first class seat for $50 with no amenities. Check out the $9 fair club, sometimes joining might pay for itself.

In our experience, Spirit's schedules have been more like guidelines. On our last trip, the flight scheduled to land at 3:30 or so did not make it until 7:30. Having said that, a check of that flight on FlightAware shows that it has been pretty close to on time for the last 7 days.

Though I hope you do not need it, a Plan B may be prudent.