Scotty,
You're staying at a very nice place. RCI Gold Crown. We switch our timesharing every year for ST.Maarten. Although I have never stayed at the flamingo, I've stayed at the Royal Palm (another sunterra property) several times. I'll be staying at the atrium this year in august for two weeks.
You're pretty much down the road from Palapa Center. You just have to come down from the resort. I do not think you will be disappointed with Dive Safaris's simpson bay location. I go in August and it's never crowded (once there were only two divers, myself and a man from paris..two people canceled). I'm not sure if May- June is still on season for SXM, July and August is def. off season.
Hope this helps. I would highly suggest renting a car! You'll see so much of the island including the French Side. Friar's Bay on the French Side is a nice beach, not very crowded, and the water is like a lake. Dawn Beach(Dutch Side) is popular with boogy-boarders since it's a little rough. They have a few beach bars, good food, and chair and snorkeling equipment rentals. Orient is probably one of the most popular beaches on the island. I don't usually go there...it's very crowded. If you're spending a few weeks on the island, I wouldn't miss Pinel Island. Pinel is an uninhabited island that you take a small boat over for the day. Great for relaxing, snorkeling, and just getting away from the normal beach. St.barts is also lovely. St.Barts seems a lot more french than the French Side. I love going there it has more ambiance and I get to practice my French!
P-burg is your best bet for duty-free liquor and jewlery. Liquor is cheaper on the Dutch Side than on the French, because the liquor stores intown (P-burg) use AMerican money instead of the Euro.
St.Maarten is also the home to some great resaurants.
if you need any more info feel free to ask.
-Christine