I vacationed on St. Maarten in March 1995 and had a grand time. I stayed at a time-share facility called the Royal Islander Club La Plage, which is located on the famous Maho Beach which abuts the runway at SXM. My balcony was offset maybe 200 meters from the centerline, and I could walk along the beach to stand under the aircraft as they landed. Since the runway is only 7,900 feet or so, and the threshold literally ends at the perimeter fence, the jets are a mere 100 feet over your head. It's the only place in the world I know of where you can be so close to heavies on short final.
You should note that while the viewing is great, the traffic frequency and variety is obviously not what you would find at a major international airport. Since St. Maarten is a jointly administered Dutch/French possession, Princess Juliana Airport has daily AF B747-300 service from Paris (at least it did in 1995), and daily KLM MD-11 service from Amsterdam. Due to the short runway, furthermore, neither service can return nonstop to Europe, so both airlines offload passengers for a quick turnaround to other Caribbean destinations. This is great for the enthusiast since you can see both services land and depart within a window of a couple of hours. One warning: do NOT stand on the beach behind departing aircraft; the proximity of the threshold means you will literally be sandblasted.
Other traffic included frequent holiday charters from Europe and Canada: Corsair B747-100s, AOM and Air Liberte DC-10-30s, Royal B727-200s, and so on. Lufthansa served the airport with what I think was a weekly A340 flight. There is regular scheduled traffic from a number of U.S. operators (NW, US, AA, CO) as well as ALM and BWIA MD-80s. There are island hoppers, of course, such as LIAT Dash 8s. I even saw a PLUNA DC-10-30 parked on the ramp, though I suspect this was a rare visitor.
Though the variety of traffic isn't great, you can't beat the spotting and photography (bring sand/salt protection for your equipment), and you get a beautiful island holiday to boot. It's a great vacation.