Are you staying on Provo? We stayed at Royal West Indies (RWI)- it's condos, right on Grace Bay. the on-site restaurant, Mango Reef, was great- but I think it has moved somewhere else. Coco Bistro, Coyaba and Da Conch Shack were all great as well. Be warned, its very expensive there. We didn't actually rent a car, took a cab one day it was like $40. And we shared it with other people.
When we went in November 2010, we did a half day excursion with Caicos Dream Tours and had such a great time. It was definitely the highlight of the trip for us. It was very easy to book via email, our tour guides were fantastic, and they pick you up right on the beach at your hotel (they also drop you off there as long as the water and wind cooperate - if not, they will drive you back from the main dock). At that time it was $70 per person, but not sure what the price is now.