I agree that it won't be like St. John. That's part of the reason we picked it (though we liked St. John).

I should add a couple more clarifications:
1. We like to stay in detached stand-alone places - not larger (or even smaller) resorts.
2. For dinner we enjoy more laid back types of places and don't need high-end (and don't enjoy too much pretense). Great outdoor atmosphere is king for us (sounds like we'll get that plenty in St. Martin).

I hadn't looked much in the Grand Case area, given number two above, but could if you think walking from non-GCBC VRBO type places in the area would be feasible. Interested in your thoughts.