Georgia--If you haven't shopped at Super U before, you're in for a treat! In general, you will not find many US brands, so be prepared for that. However, Super U is extremely well stocked for veggies, wine, every kind of cheese on the planet, etc. The selection of liquor isn't nearly as large as Carrefour, however. As far as mixers, they have Super U brand stuff that works fine. I don't drink Bloody Mary's, so haven't looked for BM mix there.

I assume you know there is a Super U in Hope Estate, as well as the one in Marigot. Hope Estate is a bit closer than Marigot from Happy Bay, and no traffic to get there. I haven't been there myself, but I understand that there is a store right there by the Super U in Hope Estate, with many pre-made goodies. If you are stuck for something that is a US made product, you should check at Petit Casino in Orient Village. I would bet they have Bloody Mary mix there.

Enjoy the villa!