I fully agree with you about the rain in the uk ( I have lived in the north east of England for the past 34 yrs and we have a lot of it here
I originally come from Mauritius, hence my knowledge of the mauritian weather.
The westcoast is more sheltered ie; Flic en Flac, Tamarin, Le Morne and Grand Bay and I would personally would go to one of these areas, Grand Bay would offer more night life and Flic en Flac is quite nice too. The temperatures are usually about 2 degrees higher on the west coast and they have less rainy days.
Hope you find these facts useful,