Maho's area that where the night life is in Sint-Maarten.
Many Night clubs and Bars.
I would recommend the bliss for the bar or the Q Club for the night club.
There is a new place on the Main Street, Terra restaurant. On top of it the Soprano Bar.
And if you don't mind driving to Simpson Bay, try the Boathouse restaurant at Simpson, they have soft live entertainments on Fridays and Saturdays. Besides they have great seafood there...