I would propose to make some predefined, most used, workflows and workbenches. Examples for workflows could be "development of mechanical parts" or "development of mechanical machines" or "fluid simulations". A "development of mechanical parts"-workflow could have the workbenches PartDesign, Sketcher, FEM, TechDraw, Spreadsheet. More specifically you would have a combobox for selecting workflow and tab-like buttons for selecting the workbench. The workbench-tabs change with the selection of the workflow in the combobox. I had sketched a sample UI for this function to be implemented. On top of this all I would change the names of the workbenches to generic ones like Assembly instead of A2plus for example.