Well I can tell you that lots of people request Martinique and Jamaica because of their close proximity to the main areas. I don't believe all of Martinique is preferred so you can actually get in some good spots in that village and not paid for it. But that's a request and not guauranteed. That said, if your request is not made, we loved our location in Barbados, Bldg. 16 It was pretty centralized, we had two quiet pools very nearby and the main pool was about a five minute walk. We were also very close to the Custom House which was convenient at check in and check out time. The main thing I requested at this resort was a first floor room. There are no elevators at CBR! Its a lovely resort with lots of quiet pools, busstops and lovely grounds to explore and enjoy. You can't have a bad location in the end. There is also a very reliable internal bus system that you can hop on from any of the busstops if you don't feel like walking to another area from your room.
And you can see the fireworks from other places besides Jamaica. But that bridge that connects Jamaica to the main pool is a great spot, we would swim at the main pool in the evening then walk to the bridge and enjoy the fireworks. The various spots around the lake offer some good views too.
Also the busstop route varies, so you can't be sure your stop near your building will always be the first or last to be dropped off. It realluy varies and I could never figure out that one. But it didn't matter since we had very good bus service there and never had a long wait or had to stand up going or coming to and from the parks.