Hi there,
Not so fast with the compliments! So, I took a closer look, and since the pages seem to all be the same "type" of page, it doesn't look like you can make the background different on different pages.
A possible work-around would be to make the pages that you'd like to have a different background in a different page type (if you go to your different pages, you'll see Page Attributes on the right side of the Editor window, and you can select Full Width, for example.) So you may be able to make all the pages that are "Full Width" have the same background, and you only use those for certain pages. Does that make sense?
Quick question for you: why isn't Tank an option for best 'stache in the poll? Is it because he'd blow everyone else out of the water?