AFAIK, the free version will not save to common CAD formats (ie dwg)
for importing to other CAD software for final detailing and layout.
Although it is possible to do proper 2d plans in Sketchup, it is very
tedious and takes too long. Sketchup is really intended for conceptual
design and visualisation.

Free version will not save to anything but it's native format, nor will
it print at higher than screen resolution (full version printouts are
wonderfuly finely detailed).

Can you explain why you think sketch-up is not ideal for detailed 2D
plans? I found that whilst it was time consuming capturing the detail
of 3D components (e.g. a staircase), the pay off once it was done was
great. How are other approaches better/quicker?