Me too. I mix as far as I can take it without touching M/S. Then I activate the plugins on my master buss. My absolute favorite is the Slate Digital "red" buss compressor. I believe it is modeled on a Var-Mu. It has a M/S switch and never operates in any other mode. That plugin does the "glue" thing super well - especially if I am combining live tracks and samples. And what can happen for spaciousness, pulling ambience to the sides to focus the center more... The list of benefits goes on and on. I now know what I can do without M/S and then with it. I don't "finish" a track until I've explored what is possible in the space M/S enables.
When I record my piano, I often use a pair of Royer N8's in a Blumelein pair. But I decode it as M/S and can get the ambient/direct ratio exactly right before applying any finishing reverb. The resulting sound is highly satisfying.
I have looked longingly at the Zahl AM-1 mixing console just because it offers true stereo channels. Every channel has M/S processing available, including the insert sends and returns. The master bus in the same. It is SO well thought out. For someone who primarily works with stereo material, it is an amazing board.
On the mic front, I wish for a Josephson C700S. It effectively lets you do several M/S pairs in one microphone - enough to spatialize anywhere in a 5.1 system on a flat plane. That microphone sounds incredible. Not cheap. But one of the finest transducers I am aware of. It enables a true "next-level" microphone technique.