I flew Cape Air a couple of times on trips many moons ago and loved them. One time the return flight from EIS - SJU was no longer on their schedule when our trip came up (I had booked real early). They put in a special flight for the 4 of us. But my love for Cape Air isn't quite enough to offset the cost difference!

As far as SJU - EIS vs STT to EIS via ferry: I hear the arguments and probably agree with most of them concerning why the SJU route is better. In our 2018 trip (pre-COVID) The Moorings had a great set up. For a flat fee ($90 pp I think) they had a dedicated taxi for us at the airport, took us to the ferry, paid for the RTFF ticket and also the taxi to the base in Tortola. The reverse process was just as smooth. So overall I found the flying to STT trip and then taking the ferry worked great.

Now there is one downside of taking the ferry that we encountered on the 2018 trip. While we've ferried a couple of times from Red Hook (did a Secret Harbour stay for a few days before the charter) those rides were pretty smooth. The ride from CA was obviously much longer and in July 2018 we were pounding into some pretty hefty waves. One son and I thought it was pretty cool, but the wife not so much. She was very seasick the entire way. Coming back was much better since she took her Bonine before traveling.

Husker: Thanks for the pricing information. The Dolphin "hybrid" would work well for us since we may have 1 traveler that has to leave early.