If you are planning on going shopping then you will need to know when to go. On the Dutch side (Philipsburg) the shops are open Monday to Saturdays, 9am to 6pm. With the French side (Marigot) it's a little different with the shops open Monday to Saturday, 8:30am to 12:30pm & 2pm to 7pm. The one thing both sides of the island have in common is that if the cruise ships are docked, the stores will stay open longer.
Which side of the island will you shop on? If you have to pick then what you are wanting to buy will help you decide. The Dutch side (Philipsburg) is known for leather goods, electronics, camera, designer clothes, watches, and jewelry where as the French side (Marigot) is known for perfume, china crystal, jewelry, and clothes. Another thing to note is that French side is a mixture of locally made items as well as French imports.
No matter what side of the island, the best deals to be found here are loose gemstones, local art & crafts, porcelain figurines, china, crystal, watches, and island made liqueurs as well as rum.