Thank you both so much for your patience and time.

It's working on ubuntu-desktop. Thank you both for your patient assistance. I'm not sure the exact sequence of steps that effected this victory, but it was something like this:
* fire up VM configured to boot from Ubuntu ISO
* install Ubuntu
* shutdown VM
* alter VM: Settings->Storage->[select virtual optical drive]->Remove Disk From Virtual Drive
* restart VM
* Find some way to mount the GuestAdditions iso file. Still not sure how I accomplished this exactly. I think the apt-get install virtualbox-guest-additions-iso might have actually done it.
* cd to the guest additions CD/ISO (on my machine was /media/sneakyimp/VBOXADDITIONS_5.1.10_112026) and sudo ./VBoxLinuxAdditions.run
* shutdown the VM
* restart the VM

At this point the VirtualBox window that I see on my workstation (the one hosting the VM's GUI) now has additional options under View->Virtual Screen 1->Resize to WxH.

Mission accomplished.

In retrospect some of the documentation makes a lot more sense now. It could be so much better.

Would you please marked it as [SOLVED], please so other people may find it useful and we don't have to repeat the process?

then afterwords install another iso on VM then do it again. Practice makes perfect. and you'll hopefully figure out what steps are actually needed for that next time you have to do this or want to do this.