I haven't been to Belize so can't comment on that. I love St. John! Most of the island is protected because it is a National Park. Culebra is nice and I agree with other posters that it is more hippie than anti gringo. The anti gringo vibe probably comes from the Puerto Rican influences. They're not really anti, it's just a cultural difference in the way you treat tourists. Culebra is definitely different and unspoiled for the most part. Beautiful beaches. My favorite part of Culebra is Culebrita but you have to get there by boat. What about Grenada? It's actually easier to get there than people think.