The building you are staying in is perfect. You will be only a short distance from Old Port Royale - where the food court and shopping is. The main pool and pool bar area are right there too. You can rent bicycles, water boats there or you can just relax on a hammock by the water (can't swim in lake though). One of the bus stops is located just a few feet from your building. You will be happy about that when you return from the parks.
Yes, Martinique is a great location. The rooms are larger then the other Disney moderates because of there age (built in 1989). We Checked Out of Martinique 25 on June 21st and they had just begun paining the exterior of the building.
If you can ask for Jamaica. The reason being is it is a short walk and over the bridge to Ol Port Royale. But if you are using the Disney transportation, it is always the 1st builing that they stop at. It comes in handy after a long day at the parks.