Thanks everyone! Yes, we definitely will be back to St Martin. Hopefully the weather will be better this time. For some reason French side appeal to us better, but definitely we do not want to limit ourselves and will try to explore Dutch side as well.
We did look into Grand Case Beach Club initially, but based on the research we did and feedback we got from people who stayed there, we decided to go with Orient Beach hotel and we did not regret our choice! Hotel was very nice, modern, clean with excellent service and very good location. It wasn't their fault that the weather did not cooperate. As for Grand Case Beach club - we decided against it due to location - very narrow beach and not as nice neighborhood. The the water is calmer, but aside of that I think Orient Beach hotel has all the advantages. Even by looking at the pictures of the room - Orient Beach hotel looks much better. And lets admit, Grand Case is not as nice as Orient Beach - even it has many good restaurants on the street that you can be easily run over by passing cars and bikes (sidewalks? what sidewalks?) and streets leading to it you would probably think twice to park your car. Again, this was our impression, as it most likely very safe, but this is how we felt.
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I don't know now where we will end up next time when we visit St Martin, but we definitely be back! As of now it is one of our top three Caribbean destinations that we visited so far - (Cayman Islands, Aruba and St Martin), and we visited many Caribbean islands with most notable exceptions of Cuba (closed to Americans), Trinidad (not really a beach destination) and Grenada (which we plan to visit next), not counting Haiti and other few smaller destinations.

Again, thanks everyone for suggestions and feedback!

Dmitry