First of all a big "Thank You" to all who contributed to this post. Your input is proving very valuable and time-saving.
From what I gather, the West coast seems a slightly better option for the month of May (particularly for the part that relates to a 4 year old child who likes to make sand castles) although the East coast remains a viable option. This brings me to the following question which I submitted in another post: weather-wise (i.e. in terms of winds and waves) is Grand Gaube subject to the same conditions than the whole of the East coast or, in other words, is Cap Malheureux the real turning point when it comes to being protected from the prevailing winds in May in the northern part of the island?
Thanks again for all your advice.