The day that you are in VG assuming you are arriving early in the day I would rent a car. If you are coming into Spanishtown on the ferry then start at the Bath's end of the island and work your way over the mountain - definitely check out Spring Bay and Savannah Bay beach. On your way up the hill hang a right and check out the Copper Mine ruins (it's really cool) and then you're going to backtrack and head up onto the mountain and I expect you're just going to want to stop a couple of times and take in the fabulous view! If you take the "high" road you might want to stop at Hog Heaven for a drink, some snacks, and THE VIEW IS AMAZING! Coming back down into North Sound there are many other views and then end up at Leverick Bay for a drink (and more snacks) before you grab you boat back the Scrub.

Of course, this assumes that you are (1) arriving at Spanishtown, (2) can return from Leverick Bay, and (3) can grab a car at Spanishtown and return it at Leverck. I'll bet you can!

Have fun!