panels on multiple monitors
Not only would it be really nice to have panels on more than just the primary monitor in a multiple monitor configuration, this smacks of basic functionality. This is something that the core gnome-shell should be providing "out of the box".
Yes, there is (or rather was) an extension that does (did) this but that is now non-functioning in current GNOME and unsupported which is exactly why this is something that gnome-shell should be providing as core functionality.