What I find useful about Sketchup is the ability to make components. You can make a post, turn it into a component, and then just copy and paste. I wish my tablesaw could "copy and paste".
Another cool feature is that you can right click on a component, and get information on it: Like how many appear in your model. I like to make an entire copy of my model, disassemble the pieces and lay them out on 4x8 "plywood" panels (or boards or whatever) to get a cut diagram from it. Because if do that at cut time, I will inevitably waste materials.