I think your third option is right for cage placement as this separate the den and living room. And it’s very nice idea of a boing hanging in the kitchen area.
Wall decals are a great idea for what you are looking to do! I put up a wall decal in my office and I love how it looks. I say that you should go for it!
Thanks for this informative article; it is helpful enough especially to those who want their greys always happy and familiar with each and every thing.