A Virtual Desktop Manager is a natural complementary application for Circle Dock and we have been looking at them. The best that we have come across is "Dexpot" which is free for personal use and is produced by a couple of guys in Germany. In a separate topic, the Sarge explains how you can use Circle Dock to switch between Dexpot's virtual desktops and summon Dexpot's settings and ancillary windows.
However, that is not the end of the story. Following discussions with Dexpot's authors, we have decided to support Dexpot natively within Circle Dock by means of additional menu options for Circle Dock's Background, Centre Button and its optional Toggle Button. These menus, in case you've not discovered them, can be summoned by placing the mouse pointer over a "point of interest" and pressing the right mouse button.
The Background's and Toggle Button menus will contain options for switching between the virtual desktops whilst the Centre Button's menu will contain options for summoning Dexpot's dialogs and ancillary windows. Circle Dock's main settings dialog will contain a few specific options concerning Circle Dock's behaviour when Dexpot is active.
If you prefer to use Dock Items to control Dexpot, you can of course continue to do so, however the menu commands will be marginally faster and more convenient.
Regardless of how you use Dexpot, it is and will remain a completely separate product with its own support forum to which you should use to post messages regarding that program.