I know that this post is from a few years back, but since no one has responded, I wanted to post information for anyone who may need it.
We stayed there for a week at an all-inclusive resort. We had a rental car, it is hard to get around without one. There are 2 sides to the island, shaped like a butterfly, with a single bridge connecting. The traffic around this bridge is pretty bad. Most of the restaurants, hotels, and shopping are on the east side, the west side is more agricultural. There is not a lot to see and do within walking distance of the port. There is a central plaza with shops and restaurants.
Some of the activities we did were hiking to the triple falls, going to the cliffs on the north east end, a rum distillery (French style agricultural rum is the best!) Domaine de Severin, and a boat trip. The beaches are on the east side. I don't know what the cruise lines offer, but I am sure you can find something you like. The architecture will remind you of the French Quarter of New Orleans, the bouganvilla is lovely. Try some red pineapple in the market and get some columbo spice. There is a restaurant called Langouste which serves 3 types of Caribbean lobster, spiny, striped spiny, and rock. There were 3 of us and we each got one type and shared. My favorite was the rock lobster. If that is not to your taste, try some chicken columbo, it is somewhat like yellow curry. Be aware, this is a French-speaking island, not very many speak English. If you like rum, try the Ti Punch. It packs a punch!