Virtual desktops allow you to create separate workspaces on a single monitor. This is like having multiple physical desks that you can swap between instantly.
A zoomed-out "Mission Control" style switcher that keeps windows playing/live.
Allow users to group desktops into "Stacks."
Here are a few feature concepts for "Switch Desktop," ranging from quality-of-life improvements to power-user tools.
The OS learns your habits and automatically queues the relevant desktop based on your current activity.