Stay anywhere on San Pedro that you feel comfortable in & that fits your budget. Keep in mind that "Island Time" has evolved into an entirely knew format in Belize...it takes 3 days to get from here to there, set up business meetings, buy major stuff like appliances, real estate, vehicles, etc., so I hope that you have a high frustration quotient! Plus the asked for price, like all over the 3rd world, is never the selling price. I get discounts on everything from groceries, furniture/appliances, services, hotels, airfare, meals, booze, etc. etc.
Don't forget, that while Belizeans are basically friendly & honest, they come froma long line of pirates, boatwreckers, & smugglers, and scerwing an innocent Gringo is not beneath them!