Nigel and Mimsey do spend a tremendous amount of time on their cat tower, staring out the porch windows. They've got a great view, and there are so many critters to watch. My folks feed the birds year round, so there's always plenty activity to fixate on.
In the morning and eve they get deer visitors in the yard. The deer like to munch on the clover in the lawn and eat apples from the trees. The cats are mesmerized when they seem them grazing in the yard and remain frozen while the deer present. It only takes one tiny movement to startle the deer and send them scattering.
The humans love the deer, too, and even though it's a twice-daily occurrence, we always run to the windows to watch, and never grow tired of seeing them there.