The cart rentals right on the Main Street (Av Rueda Medina) and closest to the ferry terminal are more expensive, and the rates are no longer that low, unfortunately, unless perhaps for a monthly rental...

But for a large group like yours, taxis from the ferry to your hotel, between your hotel and town, or to other spots makes more sense. You should rent a few golf carts once or twice to see the island that way as it is fun. Does your hotel/resort offer carts?

"Travel changes you. As you move through this life and this world you change things slightly, you leave marks behind, however small. And in return, life — and travel — leaves marks on you.”
-Anthony Bourdain