Personally, I've found one of the more stimulating ways of playing in recent times has been to kind of move outside the free improvised area and work with people who are probably improvisers but they have a particular way of working.
“To appreciate heaven well, it's good for a person to have some fifteen minutes of hell.”
“Courtrooms contain every symbol of authority that a set designer could imagine. Everyone stands up when you come in. You wear a costume identifying you as, if not quite divine, someone special.”