Spirit has ALWAYS added lots of stuff that they don't charge you for, on other airlines. That really is not the biggest problem with them. Not sure what their schedule is for St Thomas, but for St. Maarten, they only fly once a week. If that flight is cancelled, you're in big trouble, as they don't cooperate with other airlines, so you could be stuck for a few days. And their seats are the tightest ones I've even flown in, by far!