St Lucia is phenomenal and you will LOVE Sandals. Excellent service, gourmet food, top shelf drinks, and scuba is included. What can be better. So far we have been to 4 of their resorts.
We stayed at Grande. Scuba shop staff is very attentive, gear is provided (I'm pretty sure it's included, but then again, I travel with my own). Scuba staff handles everything: tanks, your gear set up (if you let them), storage, etc...
Most Sandals run 2 trips per day: 2 tank in am and 1 tank in the afternoon. Make sure to visit the shop as soon as you arrive at the resort. Your first dive will most likely be the afternoon dive (checkout dive) on the shallower reef. May even be in the scuba pool, where you'll demonstrate the basic skills: mask removal and clearing, buoyancy control, regulator recovery, etc...
Usually you can sign up for the dives the day before. You will be there on Thanksgiving week, and they are likely to be fully booked, so make sure you sign up for the tomorrow dives BEFORE you leave the dive shop.
As for the dive sites... Most are within 20-30 minute ride from the resort. The variety covers the entire spectrum from drift, to walls, to wrecks.
My personal favorite - Superman's Flight, a great drift dive. Other great sites were the wreck of Leslene M and the Keyhole Pinnacles.
We were in St Lucia also in the end of November and the vis was 60ft max - end of hurricane season. One day the dives were actually canceled. But that's an exception.
Make sure to take advantage of Stay at one play at three policy. I did not care for Halcyon, except for The Pier Restaurant. Reserve ASAP - food is fantastic and the view is unbelievable. Plenty to do at Grande. We took the trip to the jungle including climbing and swimming in the waterfalls. Wonderful time and great memories.
Enjoy your vacation.
