Thats a hard question to answer. I live on Caye Caulker but come from a small town in Montana. I do not like all the traffic and hussle bussle of San Pedro. We have only a few service cars here these Cayes are much to small for alot of vehicles. Caye Caulker is also alot less expensive. You can actually go on a snorkle trip from here to San Pedro for less than the same trip out of San Pedro. We have upscale resorts fine dining, nightlife etc, and a go slow moto. Not to put down San Pedro, depends on what you want. If you are young and want some action, or can afford to stay in one of the many resorts south or north, rent a golf cart to get around, San Pedro is great, my kids love San Pedro, they love to Party, You did not say when you were coming but high season is just about over so traffic and Hotel prices in San Pedro will come down. I would split your trip up and visit both.Keep in mind you have posted this question on the ambergris link so most replys will be pro San Pedro, ask the same on the Caye Caulker link.