I am a very keyboard-centric person and in the world of dual monitors I am constantly sending windows and applications back and forth between monitors.
It would be extremely nice to have a keyboard shortcut to float a table, or toolbox or map or whatever is active. That way you could instantly send it to the other screen with win+shift+ arrow or move it around as you see fit.
I am a big fan of how easy it is to use multiple monitors in pro compared to Arcmap, but I find I am constantly dragging tables around because they default to the bottom of the map. I know its in the product plan to fix, but I think a shortcut would be nice as well.