Easier to fly direct to STT for sure, from the Eastern US, but all my trips there have taken me on a connection via SJU and for my part the vacation starts when we get on that tiny plane for the trip to Beef Island... the view of the islands on the approach to EIS is a great way to start the experience! Also - avoids any of the ferry hassle too. I have also picked up people who join us mid trip from the beach at Trellis bay after they have done the short walk from the airport. Also very handy.