Ron, some cruise lines do sail from other Caribbean ports to the southern Caribbean, at least this year. Princess has some cruises from Barbados. Windstar does some from St. Thomas. I think there are other cruise lines that sail some ships from Antigua.
Yes, I sailed Renaissance a couple of times in the winter in the Eastern and Western Med. It was great! No crowds, easy climbs in ports that offered acropolis' and hilly terrain, overall I really enjoyed it.