We are connecting through STT en route to STX and will have a five-hour layover on the return. Is it reasonable to leave the airport, go spend a few hours, say at the Best Western Emerald Beach, and return to clear inspection for the flight to the mainland? If we do this and our luggage is checked through to Newark, how long should we leave to clear security/passport control? Our flight from STT leaves at 1:40 PM.
Dumbest answer ever:
I think that you would have plenty of time to enjoy Emerald Beach. If you checked your luggage and just bring a swimsuit in your carry on you should be fine. It is a short walk to get there from the airport. I'd get back to the airport at minimum an hour before your flight leaves for STX, maybe even an hour and a half to be on the safe side.