Cherie - I cannot recommend enough renting that Jeep. We got a very nice one for $45 right at the pier - there are about 3 agencies right there and they will fight for your business so use that to your advantage and barter. We were able to go offroading, shop, visit ruins at San Gervasio, eat and drink at Mezcalitos (dynamite shrimp!), swim and snorkel and all at our own pace. The island is small so you just drive around it. Then when we dropped off the jeep the lot boy was nice enough to drive us to Carlos and Charlies. Renting that jeep was easily the best part of our trip.
Jim