You can actually create multiple widgets of the same type. So as many timezones or cities you want to track you can just keep adding timezone widgets.
I like the easy access of it, just click your clock and boom in 1 second you have instant access to these.
I even ordered mine based on relative closeness to my time. For example:
My local time is EST.
The extra 4 clock widget has UTC, Poland, India and Australia which are all +X hours ahead of EST in that order.