One thing to keep in mind, if you are coming from the States, there are a limited number of airlines that fly into Belize (Continental, TACA, American, US Air), so if you know there schedules, you will have a good idea about what time you will arrive in BZE. I think the only overnight flight is TACA from Los Angeles. It is an overnight flight that connects in San Salvador and arrives in BZE around 9 or 10 in the morning.