I know that Sketch-up would be great once I learned it... and I even spent about 3 hours hours trying to make a start of it. I finally gave up when I was unable to rotate a 2x4 to the proper vector.
The problem is that I've been doing orthagonal drawings for at least 45 years. I can take a pencil, a staight edge, and some graph paper and put my thoughts on paper very quickly.
I can easily visualize when I have a side and top view. Occasionally end views are needed if there's something that won't show on the side.
If I had a tool that would let me draw in 2D and convert the orthogonals to 3D I could probably manage. Even drawing in 3D would be okay if I didn't have to jump through hoops to do it. I want to do it like I do with a pencil-- draw some lines, group some of them into objects, and be done.