Hello,
I have decided to dive in and instead of using a specific Joomlabamboo template, just to work with one of the "basic" Zen Grid options to create what I need.

But now I have a perhaps silly question: what exactly is the difference between Zen "Default" and Zen "Blank" in regards to creating my own template from these?

Thanks,
Matthew

Default just has some basic margins delimiting the various sections (header, nav, main, footer, etc) and some other minimal generic styling.

Blank is just that, blank. No styling at all.

Best thing is to install both and switch between the two to see the difference. It depends what sort of site you have planned as to which will be the best starting point. Default can save you some work and provides good hints about where to place various styling, because you can see what is already there in the theme.css

I usually start working with default....