World Clock Deluxe lets you rotate clocks in the menu bar, that is display clocks alternately on the right end of the menu bar.
Choose World Clock Deluxe > Preferences, and then click Menu Bar.
Select the "Show clocks in the menu bar" and "Rotate clocks in the menu bar" checkboxes.
To adjust the time each clock is displayed, drag the time interval slider.
By default, clocks all have the same width in the menu bar. If you prefer that the width of the World Clock Deluxe menu bar item varies when clocks rotate, deselect the "Fixed width clocks" checkbox.
To show analog clocks in the menu bar, choose "Analog clocks" from the Style pop-up menu.
If you want to limit your clocks' width in the menu bar, choose "Show city/time zone/text & time" from the Format pop-up menu.
If you want to further reduce your clocks' width, select the "Truncate city/text to" checkbox to truncate city names and alternate texts to a fixed number of characters. Use the pop-up menu to specify the number of characters.
If you prefer not displaying label colors in the menu bar, deselect the "Show label" checkbox.
To gain a quick overview of clocks, click the clock in the menu bar: all your clocks will appear in a menu. If you want, you can customize the menu so that it lists only the clocks that are visible in the menu bar or, conversely, only the clocks that aren't visible in the menu bar.
Customize the World Clock Deluxe menu in the menu bar
Show and hide clocks