I have Plex lifetime sub and TIDAL sub, but never explored them in combination. Where would I start to learn more? Have you compared to Roon's or Audirvana's integration of TIDAL?

I haven't, but this thread got roon on my list to explore. I've used plex for movies for years, and google music's end got me looking for new things.

I have two music libraries: tidal and my own music (I'm using about 80% my own music). The music is well tagged already using picard, so I don't know how well that works out of the box. When I'm in the tidal library, I usually will mark an album/artist to be added to my normal music library and then it will start showing up there mixed in with my self hosted stuff.

The killer features (to me) are 1: playing by album instead of by track. I use the "random album" shuffle all the time and usually want to listen to an album all at once and 2: smart playlist builder which lets me make dynamic playlists around how many times I've played a thing, my personal rating, or when the last time I played it was.

https://imgur.com/a/7zchJC7

https://picard.musicbrainz.org/