I did some quick sketching of the possible alien invasion theme. As you can see, I'd like it to be kid friendly with a lot of humor. It should be cool for older kids as well if I go all out on the crashed UFO and War of the Worlds like machine.
Click on image to enlarge.
Here's a sketch of what the aliens could look like. Drawn with "found object" or inexpensive materials in mind such as small plastic trash cans, bowls and foam pipe insulation.
I'm still going to pursue my other themes (the Frankenstein is a favorite as well, and seems to be for others). It's good to get ideas doodled, even loosely. It helps the practical side think things out.