All Caribbean schools are not equal, there are only four programs that will allow you to work in all 50 States, they include SGU, AUC, Saba, and Ross. Overall you will wind up spending over 250K+ to get your education. I got into all of the first three programs, and after doing my research speaking to graduates and residency PDs SGU turned out to be the best choice, it has the highest graduation rate and USMLE pass rate of all these four programs. I would say Saba would be number two, followed by AUC, and then Ross would be last.
SGU's program is the most organized of the four, we recently got a lot of new clinical spots in New York, so rotations won't be hard to get. I have friend that is in AUC, its nearly a month into his first semester and his anatomy lab does not even have cadavers yet. Registration was also a mess, he had to carry nearly $1000 cash with him to buy health insurance for the year, SGU organizes all of this bureaucratic nonsense better. On campus housing is mandatory for all first semester SGU students, you are going to be in a third world country, I can't emphasize how important it is to be able to have on campus accommodation for at least the first semester. AUC has it on first come first serve basis. Ross does not have any accommodation for their students on campus.
Some people say St. Maarten is more modern, there are some places that are more modern given that the island is a tourist destination. In fact a casino is located down the road from the campus. Honestly though I did not see a big difference in the livability of Grenada and St. Maarten, they are both third world countries.