I've used AutoCAD a little in the past, far from capable of teaching it to anyone. I think I'm too accustomed to Studio Max and that's why I struggled with Sketchup. But I was saying, most people I know find Sketchup very easy to use, I'm just an odd exception apparently. It's like when folks tell me to use Gimp but I've used Photoshop for close to 20 years and thus find it infinitely easier to use...I suggested AutoCAD because I believe the results to be more precise for designing technical blueprints, plus it's kind of an industry standard. I don't know many professional jobs asking for sketchup. But I have minimal experience with either so maybe I'm wrong...What I would NOT recommend for a hobbyist is StudioMax, due to price. As an alternative, there is Blender. It's been around awhile, free, and well supported. But it all depends on if he wants to do 3D modeling, or make reference designs...
What does your friend use?
I didn't mean for my post to sound so challenging (on re-read) and would offer that you probably (?most likely actually) have more "computer savvy" than I do.
What I can share "professionally" as an Architectural Designer" (I'm not an Architect by collegian training, nor wish to be) is:
1. Sketchup is more detailed (1000ths of a millimeter or smaller) than most structural designer's would ever need.
2. Our PE use Auto CAD, Solid Works and Sketchup...There go to these days for blue printing and interfacing with most clients (Timberwrights for the most part) is Sketchup...
3. All our blue prints are generated by Sketchup (this is the pro version however)
What I actually "think" from many such conversations is this: one has to understand the budgetary needs of a system in the long run, what there clients may (or may not) be able to use or afford, and what is then easiest for them to learn. Its a spectrum for sure, and for me and most areas I work in from education to architecture Sketchup has more than met the need accross the board, but I will own that is a bias because it is everywhere in my daily world from 5th grade class rooms, to libraries, and most of my collegues use it for design work...here and overseas...
Go with what fits you needs for sure!!!