The dimensions of the bookcase (stacked three high) are: 34” Wide x 16” High (12 1/2” interior) x 15” Depth (14” interior).
You might also take a look at this site. There are scans of catalogs which provide dimensions for various cases and other parts, I think there's enough info there to work out your own models for plans.
Bob, I hear you. The SketchUp plans would be useful, but there is certainly a level of customization necessary for most projects. Designing in SketchUp is almost as much fun as making sawdust.
So you take a an interesting SketchUp model (it's not a plan at this point) and customize it according to your needs (change the dimensions, how many individual cases for your wall space, etc). It's not too hard.
If you send me your current version of SU I can save my model in your version and email it to you to experiment with. Your call.