Also sketchup will give you the fundamentals for free.
I'd say it is worth it to learn the basics of anything you'll be having employees do for you. It's good to know what you're asking for and the scope so that you can connect to your employees more easily. I wouldn't become an expert at it though if you are not planning on using it too much.
Make sure you learn how to specify dimension in SketchUp when you learn it. That will save you a lot of effort, and find video tutorials on YouTube. It was much easier for me to understand it by watching the video than by reading Google's documentation.
It has a hugely active community writing custom plugins for just about everything you could imagine. My tipping point was finding all these plugins are written in Ruby :-) As a programmer I loved being able to hack together new extensions based on examining the source to other peoples work.
If you plan to do anything regarding animation, physics engines, or spline-based surface modeling etc then you'll need to look elsewhere of course. Blender is free and has a massive amount of features but a steep learning curve (and I personally dislike the interface).
CAD isn't really going to help you much unless you are planning on building prototypes yourself (even then you would probably end up having to start over if you hired someone else with actual experience.)
If you want to learn a program still, Solidworks is probably the most widely used, the two other big players for 3D are Pro/Engineer Wildfire (though I think they changed what it is called now) and Autodesk Inventor (not quite as used, also lacked major integration with FEA last time I looked).
Take a look at Betty Edward's book "Drawing on the Right Side of the Brain". It's probably the best intro around.
As a "Biz Guy" your enduring quality and contribution is to hold the vision and communicate it effectively to the specialists, be they PhotoShop or CAD skilled.
No. Learning CAD would be a highly inefficient way to improve your communication of ideas due to the steep learning curve associated with professional level products.
Playing around with Sketchup might have some benefit, so long as one recognizes that Sketchup models typically have substantial limitations as technical documents.
Also the 3D warehouse on it is awesome, for pre-loading community developed models into your own.
I do network designs in visio, 3d BIM models in revit, small home stuff in sketchup, presentation graphics and icons in inkscape.
I export visio stencils to .dwg format which we then bring into revit and turn into 3D blocks for rack elevations etc...
There are so many tools to use.
If you want professional architecture Autodesk Revit is the best for this.
If you want quick and dirty modeling, even for products, use google sketchup!
There are a lot of product designs that have been done in sketchup.