Are you going to be on STJ for a day or for a week? If you are staying for a week, rent a car. While it may not be cheap, it will enable you to see the entire island. There is no public transportation that will allow you to see all over the island.
If you are there for a day, just take a taxi. There are a handful of scooters on island but in my years of living on STJ, I can confidently say that they really are not safe. The island roads are very hilly and windy and they ar no place for a scooter.

Nidenud,
Check with Phyllis at Hillcrest, she has arranged a jeep for us in May from Courtesy Car Rental, next to guest house. What suite are you renting??

I would definitely get a vehicle and tour about in the early part of your trip. Don't let driving on the left freak you out, the speed limit is 20MPH - take it slow! If you are dead set against driving have Phyllis book a taxi tour for you.

STJ is an amazing place.

Cheers, RickG

We are renting thr front suite for 10 days in april