Just got back from a quick trip to St. Martin and had some great food. We hit many of the spots recommended in other posts and wanted to give a quick update. We stayed near Orient Bay and ended up eating exclusively on the French side. Seems like if you skip the wine and do either an appetizer or dessert with your dinner, you won't spend too much. Otherwise, expect to spend around USD$75/person.
Bistro de Caraibes : A great restaurant. They service was outstanding and the ambience is relaxed. The decor of the restaurant would make you think long pants and shoes were necessary, but people were in shorts and sandals and still felt comfortable(though nice shorts with a polo shirt). We had appetizers of escargot and a salad with baked goat cheese and smoked duck breast. Both were great. Dinner was Veal scalopini and poached red snapper in a saffron sauce with mussels. Fantastic food and great service. USD$200 with 2 appetizers, 2 entrees, 1 dessert and 3 glasses of wine.
Spiga: We thought this was a good restaurant, though not a destination restaurant. The pasta was fresh and tasted good, but had clumped together a bit when cooking. The sauces for the pasta were also good, though there was too much of it. We had a pasta with shrimp and scallops, and there was very little scallop. The dessert was fine. You won't leave disappointed, but you will likely forget the meal very soon. If you want pasta and are looking for a good dinner, as opposes to an experience, this is a good bet.
Ti Bouchon: As others have said, Momo, the owner, is great. He is friendly and welcoming and makes you feel comfortable. The ambience of the restaurant,which is situated on a wrap-around porch of a house, is a welcome change from the indoor restaurants we visited. The food that we got, the red snapper and mahi mahi, was very good. The desserts were also great and the wine selection is nice. All in all, it was a fantastic meal and I would go back there if I returned to St. Martin.
Bacchus: We went to the one on the french side. It is located in a strip mall with little character and loses points for ambience. The service was fantastic, as it was nearly everywhere we went. The food was good - we had gazpacho, crab salad, a cheese plate and macaroons for dessert- but ended up spending about $50/person for lunch. For that kind of money we thought we could have had comparable food in a better ambience. It is only open for lunch. Unless you are dying for imported French food, I would say time is better spend during the day hanging on the beach having a fish sandwich or food from a lolo.
Final review: If you head to St. Martin, definitely go to Bistro Caraibes and Ti Bouchon. You will remember those meals for a long time. Go to Spiga if you are in the mood for good pasta. Skip Bacchus - not worth the price or the trip into an industrial strip mall.