We went to St. Lucia for our honeymoon in August of 2006. We stayed at one of the three Sandal all inclusive resorts on the island, The Regency. We did take a day trip over the The Grande resort. If you stay at one of the three Sandals resorts they provide a free shuttle between the resorts and you can access any one of them for free, including the restaurants. The Grande was so pretty and I really liked that resort. If it hadn't been under construciton while we were there I think I would have preferred that resort over the Regency.
St. Lucia was beautiful and the beaches are amazing. We took a guided tour of the island with Cosol Tours. It was a great tour and we learned a lot about the people of St. Lucia, their bananna exporting and the volcano. Definitely worth the money and the time (it takes all day). My favorite excursion was the 4 hour horseback ride on the beach, however, the title of this excursion is a bit misleading. You are not on a horse for four hours, probalby about an hour total. You ride along a road and through a little wooded area to the beach. Once at the beach you dismount, enjoy a "barbecue" and a walk (on your own feet) along the beach. They have about 4 larger horses that you can ride out into the water. Mike and I both were confident enough riders that we took the horses out into the water on our own multiple times.