Make sure that your City Tour is legit. We ended up in a small 4 door car with a young kid taking us through the poorest parts of town. We felt we were about to get mugged and left for dead in a ditch somewhere. All this for just 25.00 USD per person
Fun Alternatives: Ask to see the vehicle you will be traveling in before paying. Look for tourism ID. There is some rich history in this city.
Man, Belize City on sundays is nothing but boring, I tell you. Better avoid that trip and spend some more pleasant hours on that beautiful island called Caye Caulker, instead of waisting time in the city. In fact, there was NOTHING to do there, but leaving as soon as possible, as EVERYTHING was closed there, even the lockers at the Marine Terminal, except from one or two tiny little tiendas. Despite the heat was killing.
Unique Suggestions: Leave as soon as possible.
Fun Alternatives: Better spend some more time on that beautiful island called Caye Caulker, or do a day- or half-day-trip ... but get to the airport on time (5 hours ahead is way too much though).
The best time to travel is the dry season from November to May, but this is also the busy winter tourist season, when prices rise and hotels fill up. It's cheaper to travel in summer (July to November), but keep in mind that this is hurricane season.
If somebody asks you for a smoke on the street be aware that this person also wants your wallet and your watch. Sometimes even your backpack and your shoes. Be friendly anyhow and offer a fast cigarette.