Originally Posted by
MojaveFlyer
But you've got to clear the aisle, so hovering anywhere is going to be someone else's seat

So my approach is to stand at the seat I would like, with my bag in hand and not overhead or under seat. I hope that conveys that I am looking for a swap, but not being presumptive. And always, always, always, give up the ask promptly and gracefully, with a smile, if it is declined.
I can't imagine doing this. I want the plane to take off on time, and quickly sitting in my assigned seat, as I am supposed to do, and stowing my bag increases the likelihood of that happening.