I’ve never stayed at a Sandals, so after your trip I hope you’ll write a trip report so we can see more details.
I’ve heard the diving in Jamaica isn’t wonderful, so if it was me I’d choose St Lucia over Jamaica (because I have been there and thought the diving was nice). Have you done some searching on what the weather is like in each of the locations you’re considering for January? Sometimes those searches are accurate and sometimes not. But you should be able to get an ‘idea’. Hurricane weather should be over by then either way (end of November?) but that doesn’t guarantee blue skies and following seas by any means.
Looking forward to reading about your experiences.

I’ve heard the diving in Jamaica isn’t wonderful, so if it was me I’d choose St Lucia over Jamaica (because I have been there and thought the diving was nice). Have you done some searching on what the weather is like in each of the locations you’re considering for January? Sometimes those searches are accurate and sometimes not. But you should be able to get an ‘idea’. Hurricane weather should be over by then either way (end of November?) but that doesn’t guarantee blue skies and following seas by any means.
Looking forward to reading about your experiences.
