I live with five cats. Two are geriatric, one a senior and two young ones. The two oldest cats, Ed and Lily, spend much of their time on our back deck in a yard that is fenced. They are far too old to jump it. Our senior cat, Sierra, sits on our front porch most mornings waiting for the mailman to arrive. He is covered in kisses when he finally departs. She has been content to stay on our porch or in our yard for ten years now. I trust her but keep a watch out for any changes in her habits. She does not bother the wildlife.
Our youngest two, Annie and Audrey are strictly indoor cats. It is because of these two scalliwags that I have to find ways to keep them happy and content inside.
The windows were closest to our maple trees where the birds spent time and where the sun hit most afternoons. They love these windows and can be found lounging on their seats every day.
You can place bird-feeders in the trees but to be honest, I never felt the need to. There was always plenty of action.
This window seat is on the second floor just over the shed roof. Audrey loves to sit there and watch the squirrels jump from the trees to the roof and back again. She also does a lot of snoozing here.
Another place that is perfect for a window seat or shelf with a cat bed would be at a ground-level window such as this one.
Cat window seats can be purchased at most pet stores.
So this is my first suggestion for you if you are looking to make your home more entertaining for your kitties.
Forget placing plants on all window-sills. Pick the ones that suit the seats or shelves and make your cats' day much more fun and interesting so that kitty isn't bored out of her ever-lovin' mind.
More ideas coming.