Definitely would recommend Jost. We spent the day there last year and plan to go again. Yes, STJ is perfection but Jost is just as nice.
Hi! Defintely take a day trip over to the BVIs. It is well worth it. I would suggest either Virgin Gorda or Jost Van Dyke if you are to take a chartered boat. I don't have experience with the Ferry over to Tortola or Jost. But either way, you will be glad you took the trip. Be sure to book in advance, and check out the cruise ship schedule to see when the cruise ships will be in (try and avoid those days if possible). Have fun.