the Brilliance is a wonderful ship. We have also done a 11 night caribbean cruise with her in 2002.
About the itinerary: Oranjestad, Aruba: really nice island, take a private tour over the island, not expensive and save;
Panama Canal (Cruising Canal); Cristobal Pier, Panama; Puerto Limon, Costa Rica: sorry but these port havenīt been in our itinerary, so try portreviews from this board.
George Town, Grand Cayman: here we have done a tour booked on the ship, not that spectactual, but a nice shopping place even as Aruba.
But maybe you prefer going to the beach. So also check portreviews.
But you will love the ship, the Radiance class is for me the best class.