Don't discount the learning potential from troubleshooting and carrying out repairs. All of these old beasts have full documentation in the instruction manual, and the circuits were designed by very smart people. You'll definitely learn something every time.
If someone without any experience were to embark on a restoration project, which scope(s) would you recommend?
About the full documentation, you ain't kidding! I just had a glance at the documentation of one of the old Tek scopes, and I couldn't believe how thorough it is.
One thing about trying to restore and figure everything out on those old scopes is it's all discrete components. From what I've seen, the CRT tube is probably the most complicated individual component. I assume any PCBs will just be two-layer, one on the front and one on the back. I actually love those old large size components, as opposed to today's surface mount components. My eyes have one heck of a time seeing tiny components and trying to solder them.