Is there an intermediate way of converting Visio 2D floorplans into 3D floor plans on Sketch Up?
If you gave us an example file of what a Visio 2D floor plan is someone might be interested in giving you an option.
What do you mean by intermediate?
Efficient way
Export to DWG or DXF from Visio, import into SketchUp and use that as a template for building your 3D model. A human or an advanced AI is required for interpreting the lines on a floor plan, there is no foolproof automatic way.
The most efficient way I know on skp to create 3D out of 2D floor plans is using a plugin like Dibac, doing it without plug-ins isn’t complicated as well, specially if you have a neat dwg file. I don’t know if there’s a tool that automatically converts a floor plan to a 3D model on sketchup.