I can comment on O'Plongeoir and Escape, as I've eated at both recently.

I would not put O'Plongoire in the category with some of the Grand Case restaurants. It's more of a bistro. The menu is definitly French, with andouilettes,etc, but not fancy.

Escape is not French at all. The food is very fresh and healthy: salmon, sous vide chicken, beef, and shrimp, as well as tofu and a few other vegan offerings. You chose a "protein", something from the "starch: and "veggie" lists, and a sauce, which comes on the side. They serve a standard and a large size. There are also some pre-designed plates on the menu.
The decor is lovely and sevice was good and friendly. However; these are things I can cook for myself at home and I don't consider it a French dining experience.

You might try Be Kool (for lunch,as I don't recommend the Marina Royal at night at this time) in the Marina Royal for a very good French meal, though not high end dining. It's directly across from Tropicana.