I've been using Sketch-UP for residential project for several yaers with great success both as a drawing as with clients. I haven't drawn a from-scratch elevation in Datacad in atleast a year. I just massage the Sketch-up model through schematic, then import the flat hidden-line image into Datacad for final construction documents....and they've generally been right to the inch as I'm careful about the dimensions when I create the model. I just have to adjust the line weights nad plotter colors, and do some weld-lines. And I know that it actually works in real-world three dimensions.
It's also used in this office for bath and kitchen detailing where I need to show three-dimensional relationships. I occasionally use it for compolicated three-dimensional structural detailing since having a line-drawing in-perspective is more intuitive than ortho-projection.
Datacad and Sketch-Up are a create combination both for presentation and for construction drawings. (Especially as I have never gotten the hang of 3-d Datacad....)
Here, in Czech republik we sell SketchUp as very good complement to DataCAD, especially for architects, who feel himself more as artists then as draftsmans...
Joanna Linhartova ADS Studio v.o.s. Prague Czech republik