Hey Mark,
There is definitely a party scene in Grand Baie, La Gualette, Tamarin, and Flic En Flac. However, none of these places are close to good kiting except maybe Grand Baie. The Northern lagoon up around Anse La Raie is kind of close to Grand Baie. There are several nice resorts up along the northern coast where the wind is also quite good, mostly flat (choppy) water and even a wave spot if you know where to look.
There is an ION club in the north for good reason. Beaches aren't quite as nice but the lagoon there is quiet and not too many people about. It'd be a short taxi ride into town. Most of the resorts are full board, meaning people tend to stay on resort and dont leave to go to restaurants or bars outside of the walls. This is for good reason as the choice of restaurants and bars in these resorts is pretty damn good and the food and drinks are generally fully covered.
Mauritius is a great place to go, but for partying and kiting, you need to go to some effort.

DM