What you put on your artwork is totally up to you, I'm more into simple designs but yours feel nice. I love the CP with as I think one ghost for single player and two ghosts for two player game?
I'm only worried about the quality of the pictures you use. I don't know how good the images are you have, but the links you share are not even close to what you need to print them in full size. And take in mind that upscaling is no option. You need a hires image to start with. 200 dpi is good resolution to use, its nice when printed on industrial inkjet printers and the file size is manageable.