If your ship is docked at Havensight, it is quicker to take the ferry from Red Hook. We have been to St. John twice and absolutely LOVE it! If you want to save some $$, on your way back just follow the locals off the ferry at Red Hook up to the local $2 bus. (It can look just like the regular taxis.) Ask if they are heading back to the pier area. We did this last time, and plan on taking it BOTH ways a week from today!!! You won't be sorry if you do this trip on your own . . . you can spend as much time there as you want, and you aren't in the midst of a crowd. (We went to Cinnamon and loved it even more.)
"Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did do. So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover."
My cruise photos: http://community.webshots.com/user/Sheffie100