I flew from SXM last year (admittedly with KLM). The lounge there is a contract lounge and is VERY depressing.

There are only a few high windows, so no views. Food choice is small, staff are grumpy, and you had to pay for drinks.

Personally, I would drop bags, and walk to the famous Maho beach for an hour to watch the planes take off and land. There's a bit of a party atmosphere down there. Then go through security as late as possible.

One tip: Don't stand behind an MD80 when it takes off. Those two engines close together will blow you into the sea, as I discovered