Ultimeter is the perfect combination of a utility device (including mid/side features) and a metering one (with correlation and LUFS metering), with a nice floating window (full version only), that you can use on a daily basis for all kinds of purposes, especially avoiding using channel settings for automation.
The Ultimeter device
Here is a features list:
Stereo to Mid/Side encoding-decoding (to feed plugins not able to do mid side processing, only stereo)
Separate Left/Right and Mid/Side gains and Mute
Left/Right swap
Phase revert for Left or Right
Overall width control (between full mid and full side)