You can walk to Maho beach from La Plage.
IMHO while you are at a great resort in a fun area, you will be a bit limited without a car in three major areas that St. Maarten is very well known for.....restaurants, shopping and beaches. The beaches nearby are OK, but you would need a car at least a day or two to get a flavor of some of the excellent beaches available. For my money, if I only had one day I would go to Pinel Island (some topless, but not in your face). Some other good choices are Mullet Bay (calm, sandy, near La Plage), Orient Beach (a bit of surf, lots of restaurants and activities, Topless in places, overhyped and crowded at times), Cupecoy (Very rough surf, Not a lot of beach, but really cool sandstone backdrop....no facilities).....Great Bay in Phillipsburg is actually pretty decent too.
As for restaurants, they are all over the island. We particularly liked Skipjacks on airport road and Chesterfields in Phillipsburg, both of which you would need a car or a cab to get to.
Shopping would be best in the two major cities, Marigold and Phillipsburg and both are about a 20 minute cab/car ride.
Just be aware, traffic is awful on the Western (Simpson Bay, Marigot) half of the island, especially airport road. Not so bad on the Eastern side (Phillipsburg, Orient beach, Oyster Bay). West of Simpson Bay lagoon (La Plage, Mullet Bay, Cupecoy) seemed Ok too.
As for the Butterfly farm, it is near Orient beach and Friars bay (very calm beach). My 7 yr. old loved it, my 4 yr. old not so much. There were lots of butterflies in a netted in garden about the size of a large house. Worth a visit if you are in the area, but not a special trip. No more than a 30 minute stop...my wife says 20 tops.
Anthony