Billy is not the only one with a new favorite place.
With the recent heat, I've taken to opening the bathroom window and its mini blind, and of course pushing back the covering shower curtain, all to promote fore and aft airflow through the upstairs.
Whitey assumes I do this each day to give him a new ledge to hop up to and see the outside world from. I'm little worried about him getting tangled and suffocating in the shower curtain, but I mitigate that by pushing it as far out of the way as I can.
(He's also the only one who jumps up to the half window in the stairway to look out from there.)
One other note on Billy's new kitchen hangout. I suspect much of its charm for Billy is not that he can watch us in the kitchen, but that with the added height he can see across the kitchen to what we're doing on the counters. It's far more interesting to him than a floor view, I'm sure.