Our last trip..2014... we spanned Labor day.. Late August early September... Less traffic and less people but it was SXM so it was great... Orient Beach was very crowded on Cruise Ship days... not so much on non-ship days... Club O (we took a walk) was very thin on people..

The LoLo's in Grand Case were closing Sept 1 on our trip and we were invited to a "Vacation party" where there were Hundreds of locals and only a few tourist.. One of our very fond memories of 8 trips to SXM.. Can't really comment much more than that on a full week or 2 in September but it seemed like many places were closing