Something I've run into multiple times is the need to coordinate variables and such between multiple workflows/tabs while working in the designer.
As a result, I often find myself with several tabs in the workflow designer open switching between them frequently to make sure everything matches up.
In some cases, I'll take a screenshot of something or open a remote session in another window just so I can compare the two items side-by-side.
Something that would be incredibly helpful is the ability to detach a tab from the main interface much like you can do in Visual Studio and other similar applications, or at the very least be able to utilize a grid view to do the same.
That would allow us to have tabs on multiple displays, or at least a split view on the same display, so we can compare without jumping back and forth.