Mark,
Designing in 3D is a great place to start, but could also be a bit more challenging based on your experience in building things from the ground up. If preparing the base model isn't an issue, and depending on the level of detail you are looking for, then our SketchUp plugin is a great help in completing this. We also have some really cool things in the works to elevate that workflow even more, which are scheduled to be complete the end of this year, near tradeshow time.
We have a few webinars that cover our workflows between CAD and SketchUp, but yes, the workflows do include sending things over from CAD first. I think in a lot of ways having a starting point from within CAD helps get some of the base linework handled without needing to draft fully in 3D. If you haven't checked out this webinar, it might be worth taking a peek. I will also be noting for future webinars to include a completely native workflow from within SketchUp for a complete concept design level output.
Simplified SketchUp Modeling