I love St. Lucia. Have been there 3X on cruises and once at a resort. Have done various excursions, but the best was a catamaran tour back in 2002. Sailed straight from the ship in Castries slowly up the coast, going through each inlet/cove/bay, around the Pitons and stopped at Soufriere. Ended with a bus ride up the mountains and a visit to the scenic Morne Coubaril estate.
No specific "beach time", but my wife and I laid out on the net in the front of the catamaran for the entire journey - getting lots of relaxation and sun for 2 hours - and getting to see some of the beautiful beaches from the boat.
Don't remember the name of the tour company, but it was really an amazing trip.