Well I changed my mind as to which background I will do first. I've decided that I will do the outdoor background. I'll be helping with a VBS program in a few weeks, the theme is bugs, and the outdoor background would be useful for that set up so I'm doing it now.
Below is a line drawing of what the background will look like. I plan to paint the back drop with some nice bright colors.

I'll be painting the scene on 4X6 foot canvas which I've primed to ensure the canvas doesn't soak up all the paint.