Thanks for all the advice. I have the Amex points to get 4 seats at pretty much any level. I saw a Delta chart where there could be a 20,000 miles difference depending on the days of the week. If those miles levels get set and only go up, then I'll nail down the charter dates and book.

Do you know if they permit open jaw ticketing on reward tickets? My son is staying a few extra days on St. John so if we went via SJU, his return would be out of STT.

Not sure if we'll go to SJU or STT. St. Thomas has the advantage of not having to pay for those over-priced puddle jumper flights but I'm not a fan of the ferry routine after a long day of flying.

We always put an extra day on the front end to give us time to relax, get provisioning, etc., without having to rush.