We have always rented a car. The first year we just rented for 3 out of the 10 days we were there and that was plenty (we were on our honeymoon and didn't venture out too much
). When we did finally get out to see the island, we decided that when we returned, we would rent a car/jeep for the whole trip...and that's what we've done every year since. Like a lot of others, we like the freedom to come and go whenever the mood strikes.