If you are a Cuba Libre fan, then you can have the original in SXM using Havana Club
If you are rum drinkers, then I suggest you look into rhums on tthe island - made in the French Islands from cane juice vs molasses. Bacchus has a good selection - take the airport road out of GC, when you come to the main road, go across to the strip mall - Simply the grocery store used to be out front, not sure if the signage yet says Super U or not, behind you will find Bacchus, lovely edibles, excellent wine and liguor assortment, several excellent rhums as well as oddly a nice resto
Enjoy
J&B
PS, for beaches I would add Baie Rouge to your list
