Back when I worked in an office I would put up badass president pics for Fourth of July. Too lazy to find them, but stuff like Kennedy riding a robot unicorn on the moon, FDR in wheelchair themed power armor, Roosevelt gunning down big foot in a forest fire, etc.
At home, the only significant decorating I do is for Christmas. There's enough misery out there, and I choose to embrace the joy and the appeal to the better side of our nature. So we have lights, fake candles, and so on, and we put up a tree that gets a new ornament or two every year which fills it with memories. And as a finishing touch we hang a banner declaring "All creatures will make merry under pain of death"