In my classroom my center point on my main wall is a huge clock wall. It represents all of the time zones in the world and I picked a major city in each time zone. These labels go with each clock and then how I arranged it there is a string that goes from the clock and city to the actual place on a large map. I get tons of compliments all year round for my clocks and think its a great way to represent the time zones.
Even if you don't do the clocks just to have the time zones represented located on a large world map would be great!