I commuted from MTY for 2 years... I know the city well. Go to the San Pedro area. if you are located downtown, it is just south, over Indepencia (insert ghetto looking foothill). On the other side is the most posh area in all of latin america. If you are looking for local flavor, there are a multitude of restaurants downtown, I would however avoid street vendors unless you have an iron stomach. The previous posts were right about the water, nobody there drinks tap and neither should you. If you have the time go to Chinpique national forest, $20 cab ride. If you want to get around the green taxis will take you anywhere dirt cheap. I cant even drive the same distance in my airport car that cheap. Many many things to do, great food, great people, good times. PM me if you need any other suggestion.