Often times when spectating I want to switch between the same 2 tees rapidly. There could be a command "spectate_closest" that finds the tee nearest to the one you're currently spectating, and switches to it. Pressing it repeatedly would, most of the time, switch back and forth between the same 2 tees, as desired.
This sounds pretty easy/fun to implement. I might implement it eventually, but probably not in the near future.