Myself, I've got four projects I'm involved in, and a dabble in number five and six.
Sketchup is easy to learn and quite intuitive and free). Heck, I did it. You can be up and creating in hours. Over at ET there are several forums that have a lot of hints and tips as well as the latest exported needed to create the .s and .sd components. I had the most difficultly getting textures for the projects. In addition to few model makers, there are few or fewer sources of textures. If your goal is other than generic shapes, there is a wealth of info in the form of Sanborn maps, Google images and technical resources. It becomes an adventure in itself doing research.