What is the best route to travel from Simpson Bay to Grand Case. If you are going out to dinner how much time should you give yourself to get there? Where to park?

I would go over the causeway and take a left at the roundabout (2nd exit) and then through Marigot to Grand Case. I would allow 30 minutes depending on how early you go to dinner. The earlier you go, the more traffic you are likely to encounter.