I've tended to agree with you folks but I really want to be sure of the entire layout before I start painting & printing. So that I don't have all my eggs in one basket, I haven't ruled out the idea of changing the backglass theme. No matter what, I'm still planning on it being a car themed pinball machine.
Here are a couple of other designs I've played with:
If I go with a CARtoons theme I might use this for the backglass.
And then this would possibly be the playing field where all the bumpers & flippers would be.
I think I'd put these on the sides of the box.
I've also considered doing a SNAKE/MONGOOSE theme.