Let's slow things down now and dig into a slow blues in A with a "Stormy Monday" kind of feel. Even though it's slow, we still want our rhythm part to develop and progress over the course of the song.
My first chorus of comping is super sparse and gives the soloist a lot of room - and a lot of time - to tell his story. This part is made up almost entirely of small chords played on the 4th beat of this 6/8 groove. The chords are all played on upstrokes and lock tightly to the backbeat.
The second chorus builds on those backbeat stabs by adding some traditional blues changes. It doesn't require anything too fancy here to develop the rhythm part while maintaining that sweet, laid-back groove.
The harmony opens way up in the third chorus, mostly with the use of sus chords. I find that switching up the changes like this can entice a soloist to play something totally new, so it stays interesting for everybody. A good grasp of voice leading can help hold the rhythm part together beautifully as well too.